Turning The Fluorescent And [2+2] Photodimerization Properties Of Single Crystal Compounds By Crystal Engineering

This thesis selected 1,4-bis[2-(4-pyridyl)ethenyl]benzene(bpeb)and 1,3-phenylenediacrylic acid(H2pda)as the targeted molecules and studied the fluorescent and solid[2+2]photopoloymerization properties of bpeb in different co-crystal structures and selective solid[2+2]photodimerization properties of H2pda in coordination compounds.This thesis includes three parts:I,bpeb was co-crystallized with seven acids of different intensity and structure to obtain seven co-crystallized compounds and they shown colorful and strong fluorescent from blue to red light,which the fluorescence of 1,4-bpeb and 1,4-bpeb2+ in solution only luminescent blue or orange light.A linear relation was discovered between the fluorescence emission wavelengths and the ?-?stacking distances of 1,4-bpeb or 1,4-bpeb2+ by analyzing their crystal structure,which the slope is-3719 nm/nm.Furthermore,the quantum yields of seven co-crystal compounds were from 0.47 to 0.69 and the life time were in the level of nanosecond that cloud use as fluorescent materials.Co-crystallizing with different guests can extend luminescence of a fluorescent molecule and fluorescence wavelengths can be tuned.?,four coordination compounds were obtained that the organic ligand was H2pda and the metals were Mn,Co,Ni.H2pda in one of them leaved two protons to coordinate with Mn2+ and the other lost one with Mn2+,Co2+,Ni2+.The UV irradiated result shown that the coordinated part could not react but the non-coordinated part was easy to react to obtain head-to-head dimer product.It has fifteen 15 possible regio-and stereo-isomers and the purified dimer product was testified to be a pair of enantiomer by structure analyses.Particular stereo compounds containing cyclobutane can be synthesized by turning the solid[2+2]photodimerization from combining different interactions in the crystal engineering.?,bpeb was co-crystallized with m-chlorobenzoic acid(mCBA),p-ntrobenzoic acid(pNBA),5-methylisophthalic acid(MIP)and in their crystal phase,bpeb could complete solid[2+2]photopoloymerization.In the progress of UV irradiation,all the three co-crystals had a possible single-crystal-to-single-crystal transformation and the changing of the fluorescent spectra were different.The fluorescence of mCBA and MIP became stronger and blue-shift after UV irradiation,but the pNBA was quenched.The reason resulting in the two different phenomenon was that the former had no quenching functional group and the reacting bpeb could compress the non-reacting molecules that lead to intensified fluorescence,which the destruction of ?-? stacking of bpeb leaded to blue-shift;the latter was quenched by nitro,which it gradually closed to bpeb with the changing structure due to the UV irradiation.Solid[2+2]photodimerization can not only obtain polymer,but also lead to changed,intensified or quenched fluorescent.