Fluorescence Properties Of The Small Molecular And Polymers Based On The Pyrazoline Chromphore

In the past decades, five-membered, hetero-aromatic compounds containing imine(-C=N-) groups, such as pyrazoline, pyrazole, imidazole, oxazole, thiazole, triazole and so on have attracted growing attention as luminophores for optical application, duing to their electron accepting nature. For example, the pyrazoline derivatives can emit strong blue light at about 450 nm with the higher fluorescence quantum yields.In this disstation, three types of the properties of fluorescence were discussed (1) A series of compounds containing 1,3,5-triaryl-2-pyrazoline have been synthesized and they can emit strong blue light with the higher fluorescence quantum yields. Moreover, the two-photon absorption (TPA) properties of these compounds were obtained in DMF solutions with the concentration c=2×10^-4 mol/L using the two-photon-induced fluorescence measurement technique.(2) 3-(4-fluorophenyl)-1-phenyl-5-(4-(4-vinylbenzyloxy)phenyl-4,5-dihydro-1H-pyrazole(FStODO), which is a novel monomer with pyrazoline segment, was designed and synthesized. Its atom transfer radical polymerization (ATRP) initiated by a tetra-functional initiator, pentaerythritol tetrakis(2-bromoisobutyrate) (4Bri-Bu) was studied in details and characterized by 1H NMR, GPC, TG-DSC measurements. The luminescent properties of the monomer and star-polymer (PFStODO) were also studied. They show similar emission wavelength withλmax = 465 nm and the fluorescence quantum yields (Φ) were 73% (monomer) and 40% (star-polymer) respectively. Although, there's obvious emission intensity decreasing in one-photon fluorescence, the cross sections of two-photon fluorescence of star-shaped polymer are much higher than that of monomer. More interestingly, the polymer can cap gold nanoparticles using DMF as both the solvent and the reductant with HAuCl4 aqueous solution at 80 oC. Moreover, the linear polymer(PFStODO) was also designed and synthesized by ATRP, and its photoproperties also been studied.(3) Two kinds of a novel amphiphilic copolymer PEG-b-PFStODO and P(4VP-b-FStODO), which could self-assemble into nanoparticles , were synthesized.