Intramolecular exciplex formation in polyvinylcarbazole

Investigation of purity and fluorescence of poly[N6-(9H-carbazol-9-ylcarbonyl)-L-Lysine] preparations

“…It is, however, relevant to compare the present fluorescence spectra with, on one hand, those of the homopolymers poly(Ar-vinyl-9H-carbazole) (PVCz)4,28-30 and poly(Nvinyl-5H-benzo [5]carbazole) (PV5BCz)28,31 and, on the other hand, those of copolymers of IV-vinyl-9H-carbazole (VCz) with 7V-vinyl-5H-benzo[0]carbazole (V5BCz). 30,32,33 For PVCz the long-wavelength (Xmax ~420 nm) emission was attributed to an intrachain excimer state4,28,30 and the shorter wavelength (Xmax ~380 nm) emission was attributed to either a normal carbazole molecular flourescence4,30 or a second excimer emission.4,28 Depending on the polymerization conditions (radical or cationic) different fluorescence spectra were obtained for PV5BCz. For the radical polymers the spectra were composed of a second excimer fluorescence at the shorter wavelength (X = 443 nm) and a sandwich-like excimer fluorescence at the longer wavelength (X = 491 nm).28,31 The cationic polymers did not show the second excimer fluorescence, but a monomer-like structured fluorescence, at the shorter wavelength, although it did show the sandwich-like excimer fluorescence at the longer wavelength.…”

“…For the radical polymers the spectra were composed of a second excimer fluorescence at the shorter wavelength (X = 443 nm) and a sandwich-like excimer fluorescence at the longer wavelength (X = 491 nm).28,31 The cationic polymers did not show the second excimer fluorescence, but a monomer-like structured fluorescence, at the shorter wavelength, although it did show the sandwich-like excimer fluorescence at the longer wavelength. 28,31 The fluorescence behavior of a series of copolymers of VCz with VSBCz (concentration of V5BCz in PVCz ranging from 0.1 to 4.1%) has been studied by Slobodyanik et al 30,32,33 In dioxane solution the host PVCz (monomer (X = 370 nm) plus excimer (X = 410 nm) type) fluorescence was quenched by V5BCz guest units and the guest emission appeared. The guest emission spectrum was found to include two components: the monomer-type of emission of guest VSBCz units (X = 412 nm) and the emission of intramolecular exciplexes formed between the neighbouring VCz and V5BCz units (X = 430 nm).…”

“…30,32,33 In dioxane solution the host PVCz (monomer (A = 370 nm) plus excimer (A = 410 nm) type) fluorescence was quenched by V5BCz guest units and the guest emission appeared. It is, however, relevant to compare the present fluorescence spectra with, on one hand, those of the homopolymers poly(N-vinyl-9H-carbazole) ( P V C Z )~,~~-~O and poly(Nvinyl-5H-benzo[b]carbazole) ( P V~B C Z )~~,~~ and, on the other hand, those of copolymers of N-vinyl-9H-carbazole (VCz) with N-vinyl-5H-benzo[ blcarbazole For PVCz the long-wavelength ( A, , -420 nm) emission was attributed to an intrachain excimer state4,28,30 and the shorter wavelength (Amm -380 nm) emission was attributed to either a normal carbazole molecular floure~cence~~~~ or a second excimer e m i s~i o n .~!~~ Depending on the polymerization conditions (radical or cationic) different fluorescence spectra were obtained for PV5BCz.…”