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Design of Green-Emitting Salts from Substituted Pyridines: Understanding the Solid-State Photodimerization of trans-1,2-bis(4-pyridyl)ethylene |
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| Authors: | Dr Abdul Malik Puthan Peedikakkal Hasan Al-Mohsin Dr Almaz Jalilov Prof Theis I Sølling Dr Anders B Skov |
| Institution: | 1. Department of Chemistry, King Fahad University of Petroleum & Minerals, Dhahran, 31261 Saudi Arabia;2. Center for Integrative Petroleum Research, College of Petroleum & Geosciences, King Fahad University of Petroleum & Minerals, Dhahran, 31261 Saudi Arabia;3. Center for Integrative Petroleum Research, College of Petroleum & Geosciences, King Fahad University of Petroleum & Minerals, Dhahran, 31261 Saudi Arabia
Department of Stability and Analysis Development Hospital Pharmacy of the Capital Region, Marielundvej 25, 2730 Herlev, Denmark |
| Abstract: | Polymorphic salts of trans-1,2-bis(4-pyridyl)ethylene (bpe), 2 bpeH2] ? (SO4)(2HSO4) ( 1 ) and bpeH2] ? 2HSO4 ( 2 ) have been synthesized and their structures determined by X-ray crystallography. The Schmidt postulate predicts that neither of the salts will give rise to photodimerization so they can both potentially be applied as green light emitters. Despite the predictions, 1 undergoes a stereospecific solid-state photodimerization reaction with 100 % yield. This is due to UV induced combination of sliding and pedal-like movement of the pyridyl ring system that influences the alignment of C=C bonds. The sliding motion is restricted in 2 . Consequently, the green emission from 1 is completely quenched after photodimerization. It is evident that counter ions play a dominant role in dis- and enabling photodimerization; their degree of protonization and lattice placement are important solvent controlled design parameters towards crystal structures that can act as future light emitters. |
| Keywords: | Schmidt postulate solid state reaction green luminescence [2+2] photoaddition substituted pyridines |