Chemoluminescence

Akmal Firuz CttContents  Historical background   OitOccurrence in nature  Chemiluminescence - Requirements -Factors  Applications: , glow sticks   References Historical 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 explanation of CL. Mentions the CL of .  1877: B. Radziszewski studies the CL of Lophine  1888:Theterm: The term “chemiluminescence” is coined by Eilhardt Weidemann  1901: R. Dubois publishes the first paper on BL and introduces the phrases and Luciferase  1905: 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?  Emi ss ion o f lig ht by a su bs tance no t resu lting from h ea t (cold ) When?  When electron in falls back to ground state. Types?  Chemiluminescence, Bioluminescence,

Compare to and . Occurrence in nature (bioluminescence)

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

 Emission of light (usually in visible and near infrared) as a result o f a ch em. reac tion.  [A] + [B] → [◊] → [Products] + light AhA: chem iliiluminescen t precursor B: oxidant ◊: excited intermediate  Sometimes in a presence of catalyst (reduce activation energy), intermediate in electronically excited state, subsequently relax to ground state by the emission of . Requirements

 Reaction must be exothermic to produce sufficient energy to form electronically excited state. For vis ible lig ht: 160 – 320 kJ/ mo l.  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 other competiti ve nonradi a tive process tha t 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 chain  Nature of other substrates affectinggp CL pathwa y  Selected catalyst  Presence of metal ions  Temperature  pH and ionic strength  Hydrophobicity of the solvent and solution composition  Presence of energy transfer acceptor Application: Luminol (forensics) Reaction: •Luminol must be activated by hydroxide salt forming a dianion.

• ItlhdIron catalyzes hydrogen perox idtdide to decompose an dfOd form Oxygen

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

• This intermediate decomppggyg,goses from higher energy states to the ground state, emitting a photon • Floorboard treated with luminol Application: Glow sticks

 First container contains Phenyl Oxalate and dye. Glass vial contains .  Reaction produces 2 molecules of phenol and one molecule of ppyeroxyacid ester.

 Peroxyacid decompose to CO2 and releases energy which excites the dye.  Dyyygpe relaxes by releasing a photon.  Wavelength is dye dependant! Examples of dyes used: Other applications  Pharmaceutical Industry (analysis and quality control)  Clin ica l Sc ience  Detecting the photoactivity of water through its

H2O2 concentration  Detecting in the breath of Asthma Patients.  HPLC ((gHigh Performance Li quid Chromatography) Special mention: Bioluminescence  In general, involves 2 types of substances: light producing luciferin and -based catalyst luciferase.  Often the process requires the presence of other substances, such as oxygen or ATP.  Luciferin is oxidized by oxygen and reaction is catalysed by luciferase and light is emitted. Emission continues until all light is oxidised.  Reaction mechanism, luciferin and luciferase vary from organism to organism . Example:

luciferase luciferin

 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 oxyygluciferin returns to the ground state. RfReferences  Ana M. Garcia-Campp(ana (2001 ) Chemiluminescence in Analytical Chemistry  http://en.wikipedia.org/wiki/Luminol  http://en.wikipedia .org/wiki/Luciferase  http://uvminerals.org/fms/luminescence  httppyy://science.howstuffworks.com/innovation/everyday- innovations/light-stick2.htm  http://animals.howstuffworks.com/animal- facts/bio lu minesce n ce3.h tm  https://www.flickr.com/photos/jackofspades/1424860617/in/set- 72157602138715960/  http://www.chemistry -blog. com/2013/07/30/chemsummer- carnival-glow-sticks-how-do-they-work/ Thank you for your attention!