Synthesis,Characterization And Property Study Of Organic Photochromic Compounds Containing Pyrazolone-ring

Abstract In this paper, two kinds of new organic photochromic compounds containing pyrazolone-ring have beem synthesized and characterized. Their photochromic mechanisms have been discussed by analysis of their crystal structure. The relation between the structure and photochromic properties has been obtained. The paper consists of four parts. In the first part, two new photochromic compounds, 1, 3-phenyl-4-benzylidene-pyrazolone- 5 thiosemicarbazone (PPBP-TSC) and 1-phenyl-3-methyl-4-benzylidene-pyrazolone-5 S-methyl thiosemicarbazone (PMBP-smtsc) have been synthesized and characterized by elemental analysis, MS, UV spectrum, single crystal XRD. The photochromic properties and photochemical kinetics of the two compounds have been studied by powder-UV reflection spectrum under irradiation of 365 nm light. According to analysis of the crystal structure, the intermolecular proton transfer mechanism of photochromism was proposed, which is different from the Schiff base photochromic compounds. The photochromic compounds of this kind take on pyrazolone-ring as photochromic moiety, while the Schiff base photochromic compounds take on -C=N- as photochromic moiety. In the second part, a series of derivants of hydrazide containing pyrazolone have been synthesized and characterized by elemental analysis, IR spectrum, 1H NMR spectrum, MS, UV spectrum and single crystal XRD. In comparison with the photochromic compound N- (1-phenyl-3-methyl-4-benzylidene-pyrazolone-5)-salicylhydrazide and other non-photochromic compounds of N-(1-phenyl-3-methyl-4-benzylidene-pyrazolone-5)-furoylhydrazide, N- (1-phenyl-3-methyl-4-benzylidene-pyrazolone-5)-p-nitrobenzhydrazide and N-(1-phenyl-3- methyl-4-methylidene-pyrazolone-5)-salicylylhydrazide, the photochromic mechanism of the former was proposed. In the third part, two complexes [Ni(PMBP-SAL)(py)] and [Co(PMBP-smtsc)2]·2H2O have been synthesized and characterized by elemental analysis, IR spectrum, TG-DSC and single crystal XRD. According to the crystal structures, [Ni(PMBP-SAL)(py)] is a mix-ligand complex, in which pyridine is the secondary ligand with donor atom of N. Ni(Ⅱ) is slightly deformed four-coordinated square-planar geometry; in the [Co(PMBP-smtsc)2]·2H2O complex, Co(Ⅱ) is slightly distorted octahedron, and water molecules bridge the molecules of adjacent stacks through hydrogen bonds, yielding one-dimensional supramolecular chain structure. In the last part, a new compound containing two pyrazolone-rings has been synthesized and characterized by single crystal XRD and other spectral analysis techniques. The reaction mechanism of the compound was discussed.