research article synthesis, characterization...

Research ArticleSynthesis Characterization Thermochromism andPhotochromism of Aromatic Aldehyde Hydrazone Derivatives

ShaoPing Zhu Yuan Chen Jun Sun YuTing Yang and ChuanJun Yue

School of Science Changzhou Institute of Technology 1 Wushan Street Changzhou Jiangsu 213002 China

Correspondence should be addressed to ShaoPing Zhu zhushaoping18163com

Received 26 April 2016 Revised 5 July 2016 Accepted 27 July 2016

Academic Editor Davut Avci

Copyright copy 2016 ShaoPing Zhu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The Schiff bases N-(5-phenylthiazole-2-yl)-2-hydroxylnaphthaldehydehydrazone (1) N-(41015840-chloro-5-phenylthiazole-2-yl)-2-hydroxylnaphthaldehydehydrazone (2) and N-(41015840-nitro-5-phenylthiazole-2-yl)-2-hydroxylnaphthaldehydehydrazone (3) weresynthesized These compounds were characterized by using IR 1HNMR 13CNMR and MS The photochromism of thecompounds was investigated by IR and UV-visible spectrometry which is time variable under irradiation of 254 nm UV lightThe thermochromism of the compounds was studied using temperature-variable IR UV-visible spectrometry TG and differentialscanning calorimetry (DSC) The results suggested that compound 2 showed thermochromism properties and compounds 2 and3 displayed photochromism properties The relationship between the substituents species and photochromic or thermochromicproperties of these compounds was revealed as well

1 Introduction

Of the many Schiff bases o-hydroxylnaphthaldehydehydra-zone had been found to be unique classes of Schiff baseswith reversible thermochromism photochromism and otherinteresting properties It was known that Schiff bases expe-rience reversible phototransformations or thermal transfor-mations between two forms in particular between enol-imine form and keto-amine form [1]The tautomerism of theSchiff bases played an important role in their photochromicand thermochromic characteristics [2 3] When heated orreceiving ultraviolet radiation the hydrogen atom of theO-H or N-H transferred and attached to the N atom ofC=N or O atom of C=O (Scheme 2) leading to 120587-120587 chargetransfer The tautomerization between enol-imine and keto-amine achieved by proton migrating thermally or throughirradiation induction so orthohydroxyl played an importantpart on both thermochromism and photochromism of suchSchiff bases [4 5] A link betweenmolecular planar structuresand thermochromism or photochromism has been proposed[6 7] Planarity of the molecule made it possible for theproton to transfer with small energy requirement [8 9] Sub-stituents on the aromatic ringmight also have an influence onthe proton transfer [10 11]

In this study three Schiff bases (1ndash3) were synthesized(Scheme 1) The thermochromism or photochromism of thecompounds were also studied The results suggested thatalthough the compounds (1ndash3) were all o-hydroxyl Schiffbases compound 1 showed no thermochromism or photo-chromism so o-hydroxyl was not the only factor work for thethermochromic or photochromic properties the substituentspecies on the phenyl ring had great effect on such properties

2 Experimental

21 Materials and Methods All the required chemicals werepurchased from Sinopharm Chemical Reagent Co Ltd andwere used without further purification Melting points of thecompounds were determined on SGWX-4 digital micromelt-ing point apparatus FT-IR spectra were recorded on aThermo Scientific System 2000 FT-IR spectrometer NMRspectra were recorded on AVANCE III NMR spectrometerin deuterated DMSO with TMS as an internal standard at300MHz for 1H and for 75MHz for 13C LC mass spectrawere recorded on SHIMADZU LCMS-2020 MS instrumentwith resolution gt40000 FWHM The UV-visible spectra

Hindawi Publishing CorporationJournal of ChemistryVolume 2016 Article ID 8460462 8 pageshttpdxdoiorg10115520168460462

2 Journal of Chemistry

CHOOH

CHS

OHO

ROH

CH NNHS

R

a

21

3

45

67 8

910

11 12 13

14 1516 17

18

NNHCNH2

NH2CSNHNH2CCH2Br 16

99840017

998400

R = 1 H 2 Cl 3 NO2

Scheme 1

OH

CH NNHN

S

R

O

CH HNHN

N

S

R

Enol-imine Keto-amine

Compound 2Compound 3

Scheme 2 Tautomerism of aromatic aldehyde hydrazones

were measured using a TU-1901 ultraviolet spectrophotome-ter DSC analysis was performed by a DZ3335 differentialscanning calorimeter (DSC) and TG analysis was detectedby a STA449-F5TAQ600 analyzer ZF-6 UV-light analyzer(254 nm 365 nm) was used as the radiation source

22 General Procedure for the Synthesis of Aromatic AldehydeHydrazone Derivatives To a 250mL three-neck round flaskcontaining 182mg (2mmol) of aminothiourea in 25mLethanol (80) 344mg (2mmol) of 2-hydroxy-1-naphthalde-hyde was dissolved in 20mL absolute ethanol Then 2mL ofglacial acetic acid was addedThe resultingmixture was mag-netically stirred and refluxed for 4 hours The solution waspoured into a beaker and laid in ice baths for 2 hours to pre-cipitateThe solid was recrystallized from ethanol-DMF (vol-ume ratio 1 1) and dried at 40∘C 461mg golden yellow solid(yield 94) was obtained The solid was 2-hydroxy-1-naph-thaldehydethiosemicarbazone (a)

245mg (1mmol) of compound a was dissolved in 25mLabsolute ethanol and 199mg (1mmol) 120572-bromoacetophe-none or 244mg (1mmol) 2-bromo-41015840-chloroacetophenoneor 245mg (1mmol) 120572-bromo-4-nitroacetophenone in 10mLethanol was added respectively

The reaction mixture was refluxed for 30 minutes Themixture became clear in a moment Five minutes later agreat deal of solid appeared Solid (compound 1 2 or 3)was obtained after suction filtration and recrystallized withethanol-DMF (volume ratio 1 1)

23 Spectral Data

N-(5-Phenylthiazole-2-yl)-2-hydroxylnaphthaldehydehydra-zone (1) 250mg yield 726 bright yellow solid mp200ndash202∘C IR (KBr ]cmminus1) 3320 (]O-H) 3111 (]N-H) 30732971 (stretching vibration of Ar-H and thiazole-H resp)1619 (]C=N) 1611 1581 1491 1480 (Ar thiazole ring) 14091349 (rocking vibration of Ar-H and thiazole-H resp) 1319(]C-OH) 756 733 (out-of-plane ring bending vibration of

Ar-H and thiazole-H resp) 1HNMR (DMSO-d6 300MHzppm) 120575 1229 (s 1H OH) 1102 (s 1H N-H) 897 (s 1HH-C=N) 874ndash871 (d 1H thiazole-H) 789ndash786 (t 4Hnaphthalene-H) 762ndash757 (m 1H naphthalene-H) 746ndash743(d 1H naphthalene-H) 741ndash740 (d 2H benzene-H)737ndash730 (m 2H benzene-H) 725ndash722 (d 1H benzene-H)13C-NMR (75MHz DMSO-d6 ppm) 120575 1682 (C

12) 1569

(C2) 1505 (C

11) 1418 (C

14) 1348 (C

13) 1324 (C

15) 1315

(C18) 1293 (C

17 C171015840) 1291 (C

16 C161015840) 1286 (C

1) 1282 (d 119869

= 863 C5 C10) 1261 (C

4) 1239 (C

3) 1234 (C

6) 1187 (C

9)

1106 (C7) 10361 (C

8) ESIMS calculated for C

20H15N3OS

34542 found119898119911 = 34610 [M+H]+119898119911 = 36810 [M+Na]+119898119911 = 34405 [M-H]+

N-(41015840-Choro-5-phenylthiazole-2-yl)-2-hydroxylnaphthalde-hydehydrazone (2) 277mg yield 73 gray purple crystalmp 302ndash304∘C IR (KBr ]cmminus1) 3333 (]O-H) 3112 (]N-H)2921 2851 (stretching vibration of Ar-H and thiazole-Hresp) 1629 (]C=N) 1600 1580 1560 1490 (Ar thiazole ring)1469 1419 (rocking vibration of Ar-H and thiazole-H resp)1399 (]C-OH) 779 739 (out-of-plane ring bending vibration ofAr-H and thiazole-H resp) 1HNMR (DMSO-d6 300MHzppm) 120575 1227 (s 1H OH) 1094 (s 1H N-H) 896 (s 1HH-C=N) 877ndash874 (s 1H thiazole-H) 792ndash986 (t 4Hnaphthalene-H) 762ndash757 (t 1H naphthalene-H) 750ndash748(d 1H naphthalene-H) 744ndash742 (d 1H benzene-H) 740ndash737 (d 2H benzene-H) 725ndash722 (d 1H benzene-H) 706(]C-Cl)

13C-NMR (75MHz DMSO-d6 ppm) 120575 1730 (C18)

1616 (C12) 1546 (C

2) 1465 (C

11) 1386 (C

14) 1373 (C

13)

1371 (C17 C171015840) 1363 (C

16 C161015840) 1340 (C

15) 1338 (C

1) 1334

(C5) 1329 (C

10) 1325 (C

4) 1286 (C

3) 1281 (C

6) 1235 (C

9)

1153 (C7) 1091 (C


20H14N3OSCl

37986 found119898119911 = 38000 [M+H]+119898119911 = 37800 [M-H]+119898119911 = 40205 [M+Na] +

N-(41015840-Nitro-5-phenylthiazole-2-yl)-2-hydroxylnaphthaldehyde-hydrazone (3) 306mg yield 784 shallow orange crystalmp 257ndash259∘C IR (KBr ]cmminus1) 3309 (]O-H) 3118 (]N-H)

Journal of Chemistry 3

2921 2851 (Ar-H thiazole-H) 1619 (]C=N) 1601 1580 14991469 (Ar thiazole ring) 1521 1330 (stretching vibrationof the nitro group) 1439 1419 (rocking vibration of Ar-Hor thiazole-H) 1371 (]C-OH) 777 746 (out-of-plane ringbending vibration of Ar-H and thiazole-H resp) 1HNMR(DMSO-d6 300MHz ppm) 120575 1236 (s 1H OH) 1089 (s1H N-H) 896 (s 1H H-C=N) 882ndash880 (d 1H thiazole-H) 832ndash829 (d 2H naphthalene-H) 816ndash813 (d 2Hnaphthalene-H) 789ndash786 (d 2H naphthalene-H) 777 (s1H benzene-H) 762ndash757 (t 1H benzene-H) 742ndash737 (t1H benzene-H) 725ndash722 (d 1H benzene-H) 13C-NMR(75MHz DMSO-d6 ppm) 120575 1686 (C

18) 1569 (C

12) 1491

(C2) 1467 (C

11) 1419 (C

14) 1410 (C

13) 1325 (C

17 C171015840)

1315 (C16 C161015840) 1293 (C

15) 1287 (C

1) 1282 (C

5) 1269

(C10) 1246 (C

4) 1239 (C

3) 1237 (C

6) 1186 (C

9) 1106

(C7) 1086 (C


20H14N4O3S 39042

found 119898119911 = 39110 [M+H]+ 119898119911 = 38895 [M-H]+ 119898119911 =41325 [M-Na]+

3 Results and Discussion

31 Thermochromism

311 IR Spectroscopic and TG Studies The color of com-pound 2 changed from gray purple to brown after beingheated to 229∘C and restored the original color after cool-ing To investigate the thermochromism of the compoundsthoroughly KBr tablets of 1ndash3 were heated to certain tem-peratures on the electric hot plate then the IR spectra weremeasured promptly The IR spectra of 2 were shown inFigure 1(a) Compound 2 had the characteristic stretchingband of hydroxyl group (O-H) at 3333 cmminus1 When com-pound 2 was heated to 140∘C the absorption peak intensityof hydroxyl group absorption peak decreased partly the resultof a conversion of the hydroxyl group to the carbonyl group(Scheme 2) When the temperature reached 200∘C the bandalmost disappeared When compound 2 was heated to 60∘Ca small absorption peak appeared at 1763 cmminus1 This was dueto the stretching vibration of the carbonyl of the keto-aminewhich was produced from enol-imine of compound 2 onheating [12ndash14]

In fingerprint region (Figure 1(b)) small new absorptionpeaks appeared at 756 cmminus1 and 695 cmminus1 while the peakat 652 cmminus1 diminished All of these changes were ascribedto the bending vibration of the C-H bond of the losingaromaticity ring of the keto-amine [12ndash14]

Figure 2 was the TG curve of compound 2 The TG curvesuggested that there was a loss weight in the beginning ofthe test The loss weight had relations to the loss of thecrystal water in the molecule Because the band of crystalwater in IR spectra overlapped that of hydroxyl group thereduction of the intensity at 3333 cmminus1 in Figure 1(a) wasabout more than the loss of crystal water Similar intensitychanges could be observed in Figure 7 By photoirradiationthe absorption peak intensity at 3333 cmminus1 of unheatedcompound 2 became smaller gradually without the loss ofcrystal water So the intensity decreased partly because ofthe tautomerism and Figure 4 confirmed the discussion as

4000 3500 3000 2500 2000 1500 1000 50010

20

30

40

50

60

3333

Tran

smitt

ance

()

25∘C

60∘C

90∘C

140∘C

200∘C

Wavenumber (cmminus1)

(a)

Tran

smitt

ance

()

750 700 650 600 550 500

30

40

50

60

B

652

D

E

C

A

25∘C (A)

60∘C (B)

90∘C (C)

140∘C (D)

200∘C (E)


756 cmminus1

695 cmminus1

(b)

Figure 1 The IR spectra of compound 2 on heating in the wholespectra range investigated (a) and in the narrowed range (b)

wellThe band at 3333 cmminus1 in Figure 1(a) almost disappearedwhen temperature rose to 200∘C It was still the result ofthe loss of the crystal water and tautomerism All the crystalwater lost at this moment and maybe most enol-imine formof compound 2 changed to enol-amine form

When the temperature rose to 337∘C compound 2 lostweight again because it started to decompose

312The DSCMeasurement TheDSC curves of compounds1ndash3 were shown in Figure 3 Compound 2 exhibited threeendothermic peaks at 229∘C 303∘C and 343∘C respectivelyThe first endothermic peak at 229∘C corresponded to colorchange temperature the second and the third endothermicpeak corresponded to the melting point and decompositiontemperature respectively The results further confirmed thatcompound 2 showed thermochromism The melting point


50

60

70

80

90

100

Relat

ive w

eigh

t (

)

337∘C

Temperature (∘C)0 100 200 300 400 500 600 700 800 900

Figure 2 The TG curve of compound 2


Compound 3

602

343303229

minus8

minus6

minus4

minus2

0

2

Hea

t flow

(mW

)

258

201

T (∘C)0 100 200 300 400 500 600 700

Figure 3 The DSC curves for compounds 1ndash3

peaks for compounds 1 and 3 were 201∘C and 258∘C respec-tively There was another endothermic peak at 602∘C forcompound 3 which was a decomposition peak

313 UV-Visible Spectroscopic Studies The UV-visible spec-tra of orthohydroxylated Schiff bases existing mainly as enol-imine structure indicated the presence of bands at lt400 nmHowever the compounds existing as either keto-amine ormixture of enol-imineketo-amine forms showed a new bandat gt400 nm [15] Photochromism or thermochromism wasthe phenomenon of chromatic change due to the reversiblephotoisomerization or thermomerization between the twotautomers which showed different absorption bands andabsorbance changes of the bands [16ndash20]

000

005

010

015

020

025

030

484

378

Abs

Wavelength (nm)300 400 500 600 700

30∘C

50∘C

70∘C

90∘C

100∘C

110∘C

Cool down to 30∘C

Figure 4 The UV-vis spectra of compound 2 on heating

Figure 4 showed the UV-visible absorption spectrachange of compound 2 on heating The yellow DMF solu-tion of compound 2 (concentration 10 times 10minus5molL pathlength 1 cm) transformed to light orange The intensity ofthe absorption peak at 378 nm decreased and a new bandappeared at 484 nm The absorption peak intensity of thenewband became greater with temperature risingTheheatedsolution was left to rest for enough time to cool down toroom temperature and the color of the solution came back toyellow UV-visible absorption spectra were tested again Theresult was showed in Figure 4 as well The absorption curveof the cooled compound 2 was compared with that of theunheated compound 2 and they agreed well These indicatedthat compound 2 had reversible thermochromism

32 Photochromism

321 UV-Visible Spectroscopic Studies Figures 5 and 6showed the UV-visible absorption spectra changes of com-pounds 2 and 3 upon irradiation of 254 nm UV light respec-tively The yellow DMF solution of compound 2 (concentra-tion 10 times 10minus5molL path length 1 cm) transformed to paleorange under the UV light The intensity of the absorptionpeak at 378 nmdecreased and a newband appeared at 480 nmwhich kept increasing as the exposure time went on

The orange red DMF solution of compound 3 trans-formed to orange yellow under the UV light (concentra-tion 10 times 10minus5molL path length 1 cm) Furthermore theintensity of the absorption peak at 469 nm became smallerwhile the absorption peak at 377 nm increased graduallyThe changes of the absorption peaks of compounds 2 and 3supported that the two compounds underwent tautomerismBecause the ratio of keto-amine form of compound 2increased under UV irradiation the absorbance of the peak


480

378

Restoration

000

005

010

015

020

025

030

Abs

Wavelength (nm)300 400 500 600 700

120min

90min

60min

30min

0min

Figure 5 The UV-vis spectra of compound 2 after a period ofexposure to UV light

Restoration

000

005

010

015

020

025 377

469

Abs

Wavelength (nm)300 400 500 600 800700

120min

40min

80min

0min


at greater than 400 nm increased For the same reason theratio of the enol-imine form of compound 3 increased whilethe keto-amine decreased after irradiation of UV light [21]

The UV light was removed after the solutions exposureto it for two hours The solutions were let to stand for 24hours and the UV-visible spectra of the compounds weredetected again The spectra of the restored compounds 2and 3 were also showed in Figures 5 and 6 respectivelyThe absorption curves were of close resemblance to thespectra of the compounds without irradiation with UV light

3333

120min

40min

20min

80min

60min

0min

10

0

20

30

40

50

60

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500Wavenumber (cmminus1)

Figure 7 The IR spectra of compound 2 after a period of exposureto UV light

3309

120min40min

60min0min

10

0

20

30

40

50

60

Tran

smitt

ance

()



Meanwhile the color of the solutionswas nearly back so bothof compounds 2 and 3 were reversible photochromic

322 IR Spectroscopic Studies The IR spectra of 2 and 3were taken on each exposure time by the 254 nm UV lightThe time-variable behavior of the IR spectra of compounds2 and 3 exposure to UV light was shown in Figures 7and 8 respectively In Figure 7 The hydroxyl group (O-H)stretching band was observed at 3333 cmminus1 for compound 2Upon irradiation with ultraviolet (UV) light the intensity ofthe stretching band decreased It was confirmed that the enol-imine form of compound 2 changed partially to keto-aminewhile in Figure 8 the hydroxyl group (O-H) stretching bandof compound3 at 3309 cmminus1 became greaterwhich confirmedthat part of the keto-amine turned to enol-imine form whenexposed to UV light


300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)

Figure 9 The UV-vis spectra of compounds 1 2 and 3

33 The Effect of Substituents on Thermochromism or Pho-tochromism Based on what had been discussed above com-pounds 2 and 3 showed thermochromism and compound 2exhibited photochromism both phenomena being associatedwith an intramolecular proton transfer which led to thetautomerism between the enol-imine and the keto-amine [7]But compound 1 had no similar properties Orthohydroxylwas essential for the intramolecular proton transfer Com-pounds 1 2 and 3 were all orthohydroxyl Schiff bases andtheir structures were similar except for the difference in thesubstituents on the phenyl groups so the substituent specieseffected the proton transfer as well

Figures 9 and 10 were the UV-vis spectra of compounds1ndash3 and those of the compounds exposure to the UVlight for two hours respectively The results showed thatcompound 1 existed as enol-imine form and changed littleafter irradiation Compound 2 existed as enol-imine formand transformed to keto-amine form and the conversion(120572 = (119860minus119860

0)119860

0 120572was conversion119860

0and119860were

the absorbance of a compound before and after irradiationby UV light) was nearly 11 at 378 nm As for compound 3the conversion of keto-amine to enol-imine was about 36 at469 nm

Hammett parameters (paranitro +0778 para-Cl +0227H 00) were important basis for judging substituents effectson the reaction of benzene ring For example the alkalinityof p-nitroaniline was weaker than aniline due to the chargepopulation on N atom being less and proton capacity weak-ened since the nitro groupwas a strong electron-withdrawinggroup But p-nitroaniline and p-nitrophenylhydrazine wereonly alkaline which accept proton rather than lose proton

But here it was evident that the molecule of compound 3was a system containing several aryl rings and amino groupwas not isolated If the proton on N atom could transfer adouble bond formed between the N atom and the neigh-boring C atom Meanwhile the unsaturated cyclic ketone

025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469

Figure 10The UV-vis spectra of compounds 1 2 and 3 exposure toUV light for 120min

changed to a much more stable benzene ring Furthermorethe benzene ring andC=N formed conjugated system and thewhole molecule became more stable So the proton transfercould take place [20 22ndash29]

The paranitro group made less charge population on Natom of amino group due to inductive effect and the sharedelectron pair deviate from H atom and turn to N atom whichis advantageous to the hydrogen proton on N atom goingaway

The substituent of compound 2 was a chlorine atomwhich was also an electron- withdrawing group The com-pound tended to turn enol-imine into keto-amine formWhatever the direction of the tautomerism intramolecularproton in compounds 2 and 3 transferred more readily thancompound 1

4 Conclusion

Investigations of three naphthaldehyde hydrazone derivativeswere conducted It was found that not all of the o-hydroxylSchiff bases exhibited thermochromismandphotochromismCompounds 1 2 and 3 had similar structures but thesubstituted species on phenyl ring were different Compound2 showed thermochromism and compounds 2 and 3 showedphotochromism As for compound 1 it showed no suchproperties So the substituted species was a very importantprerequisite in these properties Results of UV-visible andIR analyses showed that compound 2 existed as enol-imineform Heated to a certain temperature or exposed to UV lightfor a period of time it partially transformed to keto-aminePart of the keto-amine tautomer of compound 3 changedto enol-imine tautomer upon UV-light irradiation Of thesethree compounds the electron-withdrawing substituents onthe benzene ring seemed to help the tautomerism


Additional Points

All additional information pertaining to characterization ofthe complexes using ESI-MS technique (Figures S1 S1rsquo andS1rdquo S4 S4rsquo and S4rdquo S7 S7rsquo and S7rdquo) 1HNMR (Figures S2 S5and S8) and 13CNMR (Figures S3 S3rsquo S6 and S9) is given inSupplementary Material available online at httpdxdoiorg10115520168460462

Competing Interests

The authors declare that they have no competing interests

References

[1] M Ziołek and I Sobczak ldquoPhotochromism and hydrolysis ofaromatic Schiff base NNrsquo-bis(salicylidene) -p-phenylenediam-ine (BSP) studied in heterogeneous environmentsrdquo Journal ofInclusion Phenomena and Macrocyclic Chemistry vol 63 no 3-4 pp 211ndash218 2009

[2] D Guha A Mandal A Koll A Filarowski and S MukherjeeldquoProton transfer reaction of a new orthohydroxy Schiff base inprotic solvents at room temperaturerdquo Spectrochimica Acta PartA Molecular and Biomolecular Spectroscopy vol 56 no 14 pp2669ndash2677 2000

[3] M Z Zgierski and A Grabowska ldquoTheoretical approach tophotochromism of aromatic Schiff bases a minimal chro-mophore salicylidene methylaminerdquo The Journal of ChemicalPhysics vol 113 no 18 pp 7845ndash7852 2000

[4] S Mintova V De Waele M Holzl et al ldquoPhotochemistry of2-(21015840-Hydroxyphenyl)benzothiazole encapsulated in nanosizedzeolitesrdquoThe Journal of Physical ChemistryA vol 108 no 48 pp10640ndash10648 2004

[5] K Amimoto and T Kawato ldquoPhotochromism of organic com-pounds in the crystal staterdquo Journal of Photochemistry andPhotobiology C Photochemistry Reviews vol 6 no 4 pp 207ndash226 2005

[6] M E Kletskii A A Millov A V Metelitsa and M IKnyazhansky ldquoRole of structural flexibility in the fluorescenceand photochromism of salicylideneaniline the general schemeof the phototransformationsrdquo Journal of Photochemistry andPhotobiology A Chemistry vol 110 no 3 pp 267ndash270 1997

[7] A Elmali M Kabak E Kavlakoglu Y Elerman and T NDurlu ldquoTautomeric properties conformations and structureof N-(2-hydroxy-5- chlorophenyl) salicylaldiminerdquo Journal ofMolecular Structure vol 510 no 1ndash3 pp 207ndash214 1999

[8] N Hoshino T Inabe T Mitani and Y Maruyama ldquoStruc-ture and optical properties of a thermochromic Schiff baseThermally induced intramolecular proton transfer in the NN1015840-bis(salicylidene)-p-phenylenediamine crystalsrdquo Bulletin of theChemical Society of Japan vol 61 no 12 pp 4207ndash4214 1988

[9] QWangW Qiu JWu andM Zhang ldquoSchiff base compoundsderived from (R)-3-phenyl-2-phthalimidopropionic acid pho-tochromism solvatochromism and fluorescencerdquo Journal ofStructural Chemistry vol 24 no 1 pp 295ndash301 2013

[10] R Jin and J Zhang ldquoSubstituent effects in the tuning ofexcited-state intramolecular proton transfer and optical prop-erties of the derivatives of 2-(2-hydroxyphenyl)-5-phenyl-134-oxadiazolerdquoTheoretical ChemistryAccounts vol 124 no 5-6 pp331ndash338 2009

[11] L Kong X Ju Y Zhang J Zhao and J Xu ldquoSubstituent effect ofa donor unit on electrochemical and opto-electronic propertiesof ambipolar benzotriazole-based polymersrdquo Iranian PolymerJournal vol 25 no 5 pp 443ndash454 2016

[12] L J Bellamy The Infrared Spectra of Complex MoleculesChapman and Hall London UK 1980

[13] J P CharlesAldrich Library of FT-IR Spectra Aldrich ChemicalCo Milwaukee Wis USA 1985

[14] L V Daimay B C Norman G F William et alThe Handbookof Infrared and Roman Characteristic Frequencies of OrganicMolecules Academic Press San Diego Calif USA 1990

[15] H Unver M Yıldız A Kiraz and O Ozgen ldquoSpectroscopicstudies and crystal structure of (Z)-6-[(2- hydroxyphenylam-ino)methylene]-2-methoxycyclohexa-24-dienonerdquo Journal ofChemical Crystallography vol 39 no 1 pp 17ndash23 2009

[16] H Shoji D Kitagawa and S Kobatake ldquoSystematic study on thethermal cycloreversion reactivity of diarylethenes with alkoxyand alkyl groups at the reactive carbonsrdquo Research on ChemicalIntermediates vol 39 no 1 pp 279ndash289 2013

[17] M Yildiz ldquoSynthesis and spectroscopic studies of some newpolyether ligands of the Schiff base typerdquo Spectroscopy Lettersvol 37 no 4 pp 367ndash381 2004

[18] H Unver ldquoSynthesis and spectroscopic studies in some newSchiff basesrdquo Spectroscopy Letters vol 34 no 6 pp 783ndash7912001

[19] R Herzfeld and P Nagy ldquoRoles of the acidity and basicity of thesolvent in the solvent effect observed in the absorption spectraof certain types of Schiff basesrdquo Spectroscopy Letters vol 32 no1 pp 57ndash71 1999

[20] H Unver D M Zengin and K Guven ldquoIntramolecular hydro-gen bonding and tautomerism in 1-[N-(4-bromophenyl)]ami-nomethylidene-2(1H) naphthalenonerdquo Journal of ChemicalCrystallography vol 30 no 5 pp 359ndash364 2000

[21] H Unver M Yıldız D M Zengin S Ozbey and E KendildquoIntramolecular hydrogen bonding and tautomerism in N-(3-pyridil)-2-oxo-1-naphthylidenemethylaminerdquo Journal of Chem-ical Crystallography vol 31 no 4 pp 211ndash216 2001

[22] T Hokelek M Isiklan and Z Kilic ldquoCrystal structure of1-[N-(6-methyl-2-pyridyl)aminomethylidene] 2(1H)-naphtha-lenonerdquo Analytical Sciences vol 16 no 1 pp 99ndash100 2000

[23] J M Ortiz-Sanchez R Gelabert M Moreno and J M LluchldquoElectronic-structure and quantum dynamical study of thephotochromism of the aromatic Schiff base salicylideneanilinerdquoThe Journal of Chemical Physics vol 129 no 21 Article ID214308 2008

[24] Y Ito K Amimoto and T Kawato ldquoPrototropic tautomerismand solid-state photochromism of N-phenyl-2-aminotropo-nesrdquo Dyes and Pigments vol 89 no 3 pp 319ndash323 2011

[25] V I Minkin A V Tsukanov A D Dubonosov and V A BrenldquoTautomeric Schiff bases iono- solvato- thermo- and photo-chromismrdquo Journal of Molecular Structure vol 998 no 1ndash3 pp179ndash191 2011

[26] E Hadjoudis and I M Mavridis ldquoPhotochromism and ther-mochromism of Schiff bases in the solid state structuralaspectsrdquo Chemical Society Reviews vol 33 no 9 pp 579ndash5882004

[27] E Hadjoudis K Yannakopoulou S D Chatziefthimiou APaulidou and I M Mavridis ldquoSupramolecular control of pho-tochromism in a 120573-cyclodextrinSchiff base systemrdquo Journal ofPhotochemistry and Photobiology A Chemistry vol 217 no 2-3pp 293ndash298 2011


[28] H Unver E Kendi K Guven and T N Durlu ldquoSynthesisspectroscopic studies crystal structure and conformation anal-ysis of N-(2-fluoro-3-methoxy)-salicylaldiminerdquo Zeitschrift furNaturforschungmdashSection B Journal of Chemical Sciences vol 57no 6 pp 685ndash690 2002

[29] Y Elerman M Kabak A Elmali and I Svoboda ldquo1-[N-(4-methyl-2-pyridyl)aminomethyl-idene]-2(1H)-naphthalenonerdquoActa Crystallographica Section C Crystal Structure Communica-tions vol 54 no 1 pp 128ndash130 1998

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


CHOOH

CHS

OHO

ROH

CH NNHS

R

a

21

3

45

67 8

910

11 12 13

14 1516 17

18

NNHCNH2

NH2CSNHNH2CCH2Br 16

99840017

998400

R = 1 H 2 Cl 3 NO2

Scheme 1

OH

CH NNHN

S

R

O

CH HNHN

N

S

R

Enol-imine Keto-amine


Scheme 2 Tautomerism of aromatic aldehyde hydrazones

were measured using a TU-1901 ultraviolet spectrophotome-ter DSC analysis was performed by a DZ3335 differentialscanning calorimeter (DSC) and TG analysis was detectedby a STA449-F5TAQ600 analyzer ZF-6 UV-light analyzer(254 nm 365 nm) was used as the radiation source

22 General Procedure for the Synthesis of Aromatic AldehydeHydrazone Derivatives To a 250mL three-neck round flaskcontaining 182mg (2mmol) of aminothiourea in 25mLethanol (80) 344mg (2mmol) of 2-hydroxy-1-naphthalde-hyde was dissolved in 20mL absolute ethanol Then 2mL ofglacial acetic acid was addedThe resultingmixture was mag-netically stirred and refluxed for 4 hours The solution waspoured into a beaker and laid in ice baths for 2 hours to pre-cipitateThe solid was recrystallized from ethanol-DMF (vol-ume ratio 1 1) and dried at 40∘C 461mg golden yellow solid(yield 94) was obtained The solid was 2-hydroxy-1-naph-thaldehydethiosemicarbazone (a)

245mg (1mmol) of compound a was dissolved in 25mLabsolute ethanol and 199mg (1mmol) 120572-bromoacetophe-none or 244mg (1mmol) 2-bromo-41015840-chloroacetophenoneor 245mg (1mmol) 120572-bromo-4-nitroacetophenone in 10mLethanol was added respectively

The reaction mixture was refluxed for 30 minutes Themixture became clear in a moment Five minutes later agreat deal of solid appeared Solid (compound 1 2 or 3)was obtained after suction filtration and recrystallized withethanol-DMF (volume ratio 1 1)

23 Spectral Data

N-(5-Phenylthiazole-2-yl)-2-hydroxylnaphthaldehydehydra-zone (1) 250mg yield 726 bright yellow solid mp200ndash202∘C IR (KBr ]cmminus1) 3320 (]O-H) 3111 (]N-H) 30732971 (stretching vibration of Ar-H and thiazole-H resp)1619 (]C=N) 1611 1581 1491 1480 (Ar thiazole ring) 14091349 (rocking vibration of Ar-H and thiazole-H resp) 1319(]C-OH) 756 733 (out-of-plane ring bending vibration of

Ar-H and thiazole-H resp) 1HNMR (DMSO-d6 300MHzppm) 120575 1229 (s 1H OH) 1102 (s 1H N-H) 897 (s 1HH-C=N) 874ndash871 (d 1H thiazole-H) 789ndash786 (t 4Hnaphthalene-H) 762ndash757 (m 1H naphthalene-H) 746ndash743(d 1H naphthalene-H) 741ndash740 (d 2H benzene-H)737ndash730 (m 2H benzene-H) 725ndash722 (d 1H benzene-H)13C-NMR (75MHz DMSO-d6 ppm) 120575 1682 (C

12) 1569

(C2) 1505 (C

11) 1418 (C

14) 1348 (C

13) 1324 (C

15) 1315

(C18) 1293 (C

17 C171015840) 1291 (C

16 C161015840) 1286 (C

1) 1282 (d 119869

= 863 C5 C10) 1261 (C

4) 1239 (C

3) 1234 (C

6) 1187 (C

9)

1106 (C7) 10361 (C


20H15N3OS

34542 found119898119911 = 34610 [M+H]+119898119911 = 36810 [M+Na]+119898119911 = 34405 [M-H]+

N-(41015840-Choro-5-phenylthiazole-2-yl)-2-hydroxylnaphthalde-hydehydrazone (2) 277mg yield 73 gray purple crystalmp 302ndash304∘C IR (KBr ]cmminus1) 3333 (]O-H) 3112 (]N-H)2921 2851 (stretching vibration of Ar-H and thiazole-Hresp) 1629 (]C=N) 1600 1580 1560 1490 (Ar thiazole ring)1469 1419 (rocking vibration of Ar-H and thiazole-H resp)1399 (]C-OH) 779 739 (out-of-plane ring bending vibration ofAr-H and thiazole-H resp) 1HNMR (DMSO-d6 300MHzppm) 120575 1227 (s 1H OH) 1094 (s 1H N-H) 896 (s 1HH-C=N) 877ndash874 (s 1H thiazole-H) 792ndash986 (t 4Hnaphthalene-H) 762ndash757 (t 1H naphthalene-H) 750ndash748(d 1H naphthalene-H) 744ndash742 (d 1H benzene-H) 740ndash737 (d 2H benzene-H) 725ndash722 (d 1H benzene-H) 706(]C-Cl)

13C-NMR (75MHz DMSO-d6 ppm) 120575 1730 (C18)

1616 (C12) 1546 (C

2) 1465 (C

11) 1386 (C

14) 1373 (C

13)

1371 (C17 C171015840) 1363 (C

16 C161015840) 1340 (C

15) 1338 (C

1) 1334

(C5) 1329 (C

10) 1325 (C

4) 1286 (C

3) 1281 (C

6) 1235 (C

9)

1153 (C7) 1091 (C


20H14N3OSCl

37986 found119898119911 = 38000 [M+H]+119898119911 = 37800 [M-H]+119898119911 = 40205 [M+Na] +

N-(41015840-Nitro-5-phenylthiazole-2-yl)-2-hydroxylnaphthaldehyde-hydrazone (3) 306mg yield 784 shallow orange crystalmp 257ndash259∘C IR (KBr ]cmminus1) 3309 (]O-H) 3118 (]N-H)



18) 1569 (C

12) 1491

(C2) 1467 (C

11) 1419 (C

14) 1410 (C

13) 1325 (C

17 C171015840)

1315 (C16 C161015840) 1293 (C

15) 1287 (C

1) 1282 (C

5) 1269

(C10) 1246 (C

4) 1239 (C

3) 1237 (C

6) 1186 (C

9) 1106

(C7) 1086 (C


20H14N4O3S 39042

found 119898119911 = 39110 [M+H]+ 119898119911 = 38895 [M-H]+ 119898119911 =41325 [M-Na]+


31 Thermochromism




4000 3500 3000 2500 2000 1500 1000 50010

20

30

40

50

60

3333

Tran

smitt

ance

()

25∘C

60∘C

90∘C

140∘C

200∘C


(a)

Tran

smitt

ance

()

750 700 650 600 550 500

30

40

50

60

B

652

D

E

C

A

25∘C (A)

60∘C (B)

90∘C (C)

140∘C (D)

200∘C (E)


756 cmminus1

695 cmminus1

(b)






50

60

70

80

90

100

Relat

ive w

eigh

t (

)

337∘C

Temperature (∘C)0 100 200 300 400 500 600 700 800 900



Compound 3

602

343303229

minus8

minus6

minus4

minus2

0

2

Hea

t flow

(mW

)

258

201

T (∘C)0 100 200 300 400 500 600 700




000

005

010

015

020

025

030

484

378

Abs

Wavelength (nm)300 400 500 600 700

30∘C

50∘C

70∘C

90∘C

100∘C

110∘C

Cool down to 30∘C



32 Photochromism




480

378

Restoration

000

005

010

015

020

025

030

Abs

Wavelength (nm)300 400 500 600 700

120min

90min

60min

30min

0min


Restoration

000

005

010

015

020

025 377

469

Abs

Wavelength (nm)300 400 500 600 800700

120min

40min

80min

0min




3333

120min

40min

20min

80min

60min

0min

10

0

20

30

40

50

60

Tran

smitt

ance

()



3309

120min40min

60min0min

10

0

20

30

40

50

60

Tran

smitt

ance

()






300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)




0)119860


0and119860were




025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469





4 Conclusion



Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



18) 1569 (C

12) 1491

(C2) 1467 (C

11) 1419 (C

14) 1410 (C

13) 1325 (C

17 C171015840)

1315 (C16 C161015840) 1293 (C

15) 1287 (C

1) 1282 (C

5) 1269

(C10) 1246 (C

4) 1239 (C

3) 1237 (C

6) 1186 (C

9) 1106

(C7) 1086 (C


20H14N4O3S 39042

found 119898119911 = 39110 [M+H]+ 119898119911 = 38895 [M-H]+ 119898119911 =41325 [M-Na]+


31 Thermochromism




4000 3500 3000 2500 2000 1500 1000 50010

20

30

40

50

60

3333

Tran

smitt

ance

()

25∘C

60∘C

90∘C

140∘C

200∘C


(a)

Tran

smitt

ance

()

750 700 650 600 550 500

30

40

50

60

B

652

D

E

C

A

25∘C (A)

60∘C (B)

90∘C (C)

140∘C (D)

200∘C (E)


756 cmminus1

695 cmminus1

(b)






50

60

70

80

90

100

Relat

ive w

eigh

t (

)

337∘C

Temperature (∘C)0 100 200 300 400 500 600 700 800 900



Compound 3

602

343303229

minus8

minus6

minus4

minus2

0

2

Hea

t flow

(mW

)

258

201

T (∘C)0 100 200 300 400 500 600 700




000

005

010

015

020

025

030

484

378

Abs

Wavelength (nm)300 400 500 600 700

30∘C

50∘C

70∘C

90∘C

100∘C

110∘C

Cool down to 30∘C



32 Photochromism




480

378

Restoration

000

005

010

015

020

025

030

Abs

Wavelength (nm)300 400 500 600 700

120min

90min

60min

30min

0min


Restoration

000

005

010

015

020

025 377

469

Abs

Wavelength (nm)300 400 500 600 800700

120min

40min

80min

0min




3333

120min

40min

20min

80min

60min

0min

10

0

20

30

40

50

60

Tran

smitt

ance

()



3309

120min40min

60min0min

10

0

20

30

40

50

60

Tran

smitt

ance

()






300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)




0)119860


0and119860were




025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469





4 Conclusion



Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


50

60

70

80

90

100

Relat

ive w

eigh

t (

)

337∘C

Temperature (∘C)0 100 200 300 400 500 600 700 800 900



Compound 3

602

343303229

minus8

minus6

minus4

minus2

0

2

Hea

t flow

(mW

)

258

201

T (∘C)0 100 200 300 400 500 600 700




000

005

010

015

020

025

030

484

378

Abs

Wavelength (nm)300 400 500 600 700

30∘C

50∘C

70∘C

90∘C

100∘C

110∘C

Cool down to 30∘C



32 Photochromism




480

378

Restoration

000

005

010

015

020

025

030

Abs

Wavelength (nm)300 400 500 600 700

120min

90min

60min

30min

0min


Restoration

000

005

010

015

020

025 377

469

Abs

Wavelength (nm)300 400 500 600 800700

120min

40min

80min

0min




3333

120min

40min

20min

80min

60min

0min

10

0

20

30

40

50

60

Tran

smitt

ance

()



3309

120min40min

60min0min

10

0

20

30

40

50

60

Tran

smitt

ance

()






300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)




0)119860


0and119860were




025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469





4 Conclusion



Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


480

378

Restoration

000

005

010

015

020

025

030

Abs

Wavelength (nm)300 400 500 600 700

120min

90min

60min

30min

0min


Restoration

000

005

010

015

020

025 377

469

Abs

Wavelength (nm)300 400 500 600 800700

120min

40min

80min

0min




3333

120min

40min

20min

80min

60min

0min

10

0

20

30

40

50

60

Tran

smitt

ance

()



3309

120min40min

60min0min

10

0

20

30

40

50

60

Tran

smitt

ance

()






300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)




0)119860


0and119860were




025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469





4 Conclusion



Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


300 400 500 600 700

025

020

015

010

005

000

378

469


Compound 3

Abs

Wavelength (nm)




0)119860


0and119860were




025

020

015

010

005

000

Abs

300 400 500 600 700


Compound 3

Wavelength (nm)

378

469





4 Conclusion



Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Additional Points


Competing Interests


References








































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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