34537-14-9Relevant academic research and scientific papers
Laser Flash Photolysis of trans-1,2-Bis(4-pyridyl)ethylene in Aqueous Solution
Goerner, Helmut,Elisei, Fausto,Mazzucato, Ugo
, p. 4000 - 4005 (1991)
Reactions of trans-1,2-bis(4-pyridyl)ethylene (neutral form: M) and its conjugate acids, HM+ and H2M2+, following excitation by laser pulses, were studied in aqueous solution.The initial photoreaction of M (at pH > 7, λexc = 248 nm) is photoionization in a one quantum process, thereby forming the radical cation (λmax = 325 nm, lifetime 80 ns) and the hydrated electron (e-aq) in low quantum yield (0.01).The H adduct radical (HM., λmax = 455 nm) is formed by addition of e-aq to M followed by protonation with water, as in pulse radiolysis.HM. and its conjugate acid (H2M.+, λmax = 500 nm) are in equilibrium with pKa = 9.8 in buffered solution.H2M.+ is also formed (in low yield) via biphotonic photoionization of HM+ at pH 4-5 and of H2M2+ at pH 2+ the photohydroxide (H2M+OH, λmax = 400 nm) was observed.H2M+OH is the only transient in neat aqueous solution, when photoionization does not occur (λexc = 308 nm) and decays by protonation (rate constant 7 x 107 dm3 mol-1 s-) to give the photohydrate, as is supported by time-resolved conductivity measurements.In 2-propanol/water (1:9 and 1:1, λexc = 248 or 308 nm) HM. or H2M.+, depending on pH, are mainly formed by H-atom abstraction from the alcohol involving the 1(n,?*) states of M and HM+.Excited H2M2+, however, yields H2M+OH, as it does in the absence of 2-propanol.
