Chemoluminescence

Akmal FiruzAkmal Firuz

C t tContents Historical background Historical background Luminescence

O i t Occurrence in nature Chemiluminescence - Requirements

- Factors Applications: luminol, glow sticks Bioluminescence References

Historical backgroundHistorical background Luminescence phenomena has been known since ancient times. Multiple

written references in ancient Chinese literature – “emperor’s magic paint” The first written acknowledgement of chemiluminescent reactions was

made by Aristotle who noted weak emission from some dead fungi and fish.

1663: R Boyle worked on oxygen which opened new doors for scientific 1663: R. Boyle worked on oxygen which opened new doors for scientific explanation of CL. Mentions the CL of phosphorus.

1877: B. Radziszewski studies the CL of Lophine 1888: The term “chemiluminescence” is coined by Eilhardt Weidemann 1888: The term chemiluminescence is coined by Eilhardt Weidemann 1901: R. Dubois publishes the first paper on BL and introduces the

phrases Luciferin and Luciferase 1905: M. Trautz publishes a review of known CL and BL reactions and1905: M. Trautz publishes a review of known CL and BL reactions and

attributes them to active oxygen 1928: H. O. Albrecht is attributed with the discovery and characterisation

of the chemiluminescence of luminol

Luminescence phenomena has a very long historical development!

Luminescence

What?E i i f li ht b b t t lti f h t Emission of light by a substance not resulting from heat (cold light)

When?When? When electron in excited state falls back to ground

statestate.Types? Chemiluminescence Bioluminescence Chemiluminescence, Bioluminescence,

Photoluminescence

Compare to incandescence and fluorescence.

Occurrence in nature (bioluminescence)Occurrence in nature (bioluminescence)

Fireflies, glow worms, g 90% of deep-sea creatures Bacteria Bacteria Fungi Dinoflagellate

Chemiluminescence

Emission of light (usually in visible and near infrared) lt f h tias a result of a chem. reaction.

[A] + [B] → [◊] → [Products] + lightA h il i tA: chemiluminescent precursorB: oxidant◊: excited intermediate◊: excited intermediate

Sometimes in a presence of catalyst (reduce activation energy) intermediate in electronicallyactivation energy), intermediate in electronically excited state, subsequently relax to ground state by the emission of photonthe emission of photon.

Requirements Reaction must be exothermic to produce sufficient

energy to form electronically excited state. For i ibl li ht 160 320 kJ/ lvisible light: 160 – 320 kJ/mol.

Reaction pathway must be favourable to channel the energy for the formation of electronically excited state.

Photon emission must be a favourable deactivation process of excited product (figure 3) in relation to

th titi di ti th tother competitive nonradiative process that may appear in low proportion.

For CL to occur, reaction must be sufficiently exothermic such that:

: Free Energy

: wavelength limit for excitation of luminescent species

Factors affecting chemiluminescence emission Chemical structure of CL precursor including side Chemical structure of CL precursor, including side

chain Nature of other substrates affecting CL pathwayg p y Selected catalyst Presence of metal ionsPresence of metal ions Temperature pH and ionic strengthpH and ionic strength Hydrophobicity of the solvent and solution

compositionp Presence of energy transfer acceptor

Application: Luminol (forensics)Reaction:

•Luminol must be activated by hydroxide salt forming a dianion.

I t l h d id t d d f O• Iron catalyzes hydrogen peroxide to decompose and form Oxygen

• The dianion reacts with oxygen producing the unstable organic peroxide intermediate:

• This intermediate decomposes from higher energy states to the ground state, emitting a p g gy g , gphoton

• Floorboard treated with luminolFloorboard treated with luminol

Application: Glow sticks

First container contains Phenyl Oxalate and dye. Glass vial contains Hydrogen Peroxide.Hydrogen Peroxide.

Reaction produces 2 molecules of phenol and one molecule of peroxyacid ester.p y

Peroxyacid decompose to CO2 and releases energy which excites the dye.

Dye relaxes by releasing a photon.y y g p Wavelength is dye dependant!

Examples of dyes used:Examples of dyes used:

Other applications Pharmaceutical Industry (analysis and quality Pharmaceutical Industry (analysis and quality

control) Cli i l S i Clinical Science

Detecting the photoactivity of water through its H2O2 concentration

Detecting Nitric Oxide in the breath of Asthma Patients.

HPLC (High Performance Liquid ( g qChromatography)

Special mention: Bioluminescencep In general, involves 2 types

of substances: light producing luciferin andproducing luciferin and enzyme-based catalyst luciferase.

Often the process requires Often the process requires the presence of other substances, such as oxygen or ATPor ATP.

Luciferin is oxidized by oxygen and reaction is catalysed by luciferase andcatalysed by luciferase and light is emitted. Emission continues until all light is oxidised.oxidised.

Reaction mechanism, luciferin and luciferase vary from organism to organismfrom organism to organism.

Example: Firefly

luciferase

luciferin + ATP → luciferyl adenylate+ Pyrophosphate

luciferinluciferase

luciferin ATP luciferyl adenylate Pyrophosphate luciferyl adenylate + O2 → Oxyluciferin + Adenosine monophosphate

+ light Light is emitted because the reaction forms oxyluciferin in an

electronically excited state. The reaction releases a photon of light as oxyluciferin returns to the ground state.y g

R fReferences Ana M. Garcia-Campana (2001) Chemiluminescence in p ( )

Analytical Chemistry http://en.wikipedia.org/wiki/Luminol http://en wikipedia org/wiki/Luciferase http://en.wikipedia.org/wiki/Luciferase http://uvminerals.org/fms/luminescence http://science.howstuffworks.com/innovation/everyday-p y y

innovations/light-stick2.htm http://animals.howstuffworks.com/animal-

facts/bioluminescence3.htmacts/b o u esce ce3 t https://www.flickr.com/photos/jackofspades/1424860617/in/set-

72157602138715960/ http://www chemistry blog com/2013/07/30/chemsummer http://www.chemistry-blog.com/2013/07/30/chemsummer-

carnival-glow-sticks-how-do-they-work/

Thank you for your attention!