Design,Synthesis And Properties Of Fluorescent Compounds On Nitrogen Aromatic Heterocyclic Extension

Organic luminescent materials based on nitrogen heterocyclic ligands have attracted extensive attention due to their potential applications in optical display devices,solar cells and biological probes.Because of?-?stacking,the traditional aromatic organic luminescent groups have low luminous efficiency in solid state or aggregation state.The concept of aggregation induced luminescence(AIE)successfully solved this problem,the mechanism is to limit the intramolecular movement to achieve higher fluorescence efficiency in the solid or aggregation state..Based on the investigation and analysis of a large number of domestic and foreign literatures,combined with the research direction of our research group,a series of nitrogen-containing heterocyclic metal complexes with AIE effect were designed and synthesized rationally,and their photophysical properties were systematically studied.The main contents summarized as follows.(1)By introducing alkane chains with different steric hindrances to regulate the molecular structure and properties of the target molecules,three cases based on2-(2-thienyl)imidazo[4,5-f][1,10]-phenanthroline(TIP)N-alkylation products(L1:no alkane;L2:allyl;L3:n-butyl)and their corresponding rhenium(I)complexes(Re1,Re2 and Re3)have AIE nature.The destroy of planarity and conjugation of TIP by introducing alkyl chains and the increase of steric hindrance via implanting octahedral Re(I)coordination sphere lead to the restrictions of intramolecular rotation and formation of intermolecular?-?stacking,which could be the main reasons for the AIE activation.X-ray single-crystal structures of Re1 and Re2 verify the increase of dihedral angle in the TIP skeleton from 10.8(5)^o to 22.7(1)^o as well as the different crystal packing fashions(AAAA vs ABAB)after introducing the spatial crowding allyl group.(2)Four novel D-A compounds were synthesized with 1,10-Phenanthroline as acceptor and 5-bromo-4-methyl-thiophene as donor.The influence of the length of the alkyl chain on the planarity and solubility of the compounds was analyzed by X-ray single crystal diffraction.It was proved that the longer the alkyl chain,the more damage to the planarity of the molecules,and the solubility has no direct relationship with the length of the alkyl chain.Finally,AIEE complex 3 was constructed by coordination of compound 2a with rhenium tricarbonyl,which has equilibrium of solubility and planarity.(3)One mononuclear and three 1D chain-like structure complexes,formulated as[Ag(cptpy)₂]·4H₂O(1);[Cu Cl(cptpy)₂]·H₂O(2);[Mn(cptpy)₄]·CH₃OH(3);[Re(cptpy)]·CH₃OH(4),(cptpy:4'-(4-carboxyphenyl)-2,2':6',2'-tripyridine),have been synthesized under the solvothermal conditions and room temperature volatilization.Complexes 1-3 show variant chain-like structures with 1D linear chain,1D zig-zag chain and 1D dimeric chain,respectively.Complex 4 are mononuclear molecule where the deprotonated carboxylate unit is free of coordinative bond.Among them,complex 1 is extended to 3D network structure through?-?stacking,and complexes 2 and 3 are further extended to 3D supramolecular network structure through?–?stacking and hydrogen bond interaction.