Syntheses,Structure And Photo-electric Property Of Co/Cu Coordination Polymers Based On N-heterocyclic Straight-chain Unsaturated Carboxylate

Choosing Co(Ⅱ)/Cu(Ⅱ)ions with absorption at different wavelength range as central metals,ten new polymers have been synthesized by the hydrothermal reaction.These polymers are based on the N-heterocyclyl flexible unsaturated carboxylic acid(3-(3-pyridyl)acrylic acid)as bridging ligand together fumaric acid as co-ligand.With small molecules O2-and CN-as bridging ligands,three novel polymers have been synthesized with conjugated N-heterocyclic compounds(phen and bipy)as co-ligands.Polymers were structurally characterized by single crystal X-ray diffraction.The formulas are presented as following:(1)[CoFe(pda)4(H2O)4]n(8)[Cu(pda)2(H2O)2]n(2)[CoNi(pda)4(H2O)4]n(9)[Ni2(pda)4(H2O)4]n(3)[Co2(pda)4(H2O)4]n(10)[Ni(pda)2(H2O)4](4)[Co(pda)2(H2O)2]n(11)[Cu(Hpda)(O2)]n(5)[Co(pda)(C4H4O4)(H20)]n(12)[Cu3(phen)(CN)2(O2)]n(6){[Co(pda)2(H2O)4].2H2O}(13)[Cu2(4,4’-bipy)(CN)2]n(7)[Cu(pda)2(H2O)2]n The structural analyses for the thirteen polymers show that polymers(1)-(3)are Co-M homo/hetero metallic coordination polymers bridged by Hpda ligand with 3D structure.Polymers(4)-(6)are mononuclear coordination polymers with Co(II)ion as a central metal.Polymers(7)and(8)are Cu(Ⅱ)1D-polymers bridged by pda-with different coordination modes.Polymer(11)is constructed from Cu(Ⅱ),pda_and O2-ions,possessing 1D structure.Polymers(12)and(13)are Cu(Ⅰ)coordination polymers bridged by CN-ion with 2D and 3D structure,respectively.The polymers are characterized by IR,UV-Vis-NIR,SPS and FISPS,XRD,TG and FP and analyzed on the basis of crystal structure data.SPS and FISPS properties as well as their effect factors are discuss.During investigating the correlationship between structure and photo-electric property,the following are induced:[1].There were photovoltage responses in the range of 300～800nm under the inducement of UV-Vis light in thirteen polymers,which indicates they all possess photo-electric conversion properties.[2].There has a good correlationship between SPS and UV-Vis-NIR absorption spectra,regarding the peak position and numbers.[3]The structural dimension of polymers influences the performance of SPS and FISPS.The 3D framework building from coordination bonds benefits to the transmission of photo-generated carriers,which leads to the width of response bands are widened.For example,in polymers(3),(4)and(6),the three polymers are constructed by the Co(II)unit with the same coordination environment(CoO4N2)and Hpda ligand.The difference is that the 3D structure of(3)is wholly connected by coordination bonds and covalent bonds,while(4)is connected by coordination bonds and covalent bonds into 1D structure,then by the H-bond connecting into 2D.The 2D structure of(6)is completely networked by hydrogen bonds.As a result,the strength and width of response band,(3)>(4)>(6).[4]The ligands of different kinds affect the SPS and FISPS.Introduction of second conjugative ligand may enhance the light absorption of coordination polymers in the visible region,i.e.,electron transition from intraligands.It can not directly form voltage,but can transfer energy,which is in favor of the transmission of photo-generated carriers.The response bands are widened and strengthen.For example,for(4)and(5)with Co(II)ions,both have 1D structure.However,(5)is introduced a second ligand-fumaric acid radical,and the fumaric acid as a structure-supporting ligand forming 1D ladder-double-chains.The structural difference is reflected by the behavior of SPS.Compared to response bands of(4),those of(5)are shifted to visible region.Another example,the response bands of(13)are shifted towards the visible region,compared with those of(11)because polymer(13)is bridged by 4,4’-bipy that has better conjugation.[5]The performance of SPS and FISPS are influenced by the extent of crystal packing.The closer the arrangement of atoms,the better the transmission of photo-generated carriers,and then the response band are wider and stronger.For example,for(7)and(8),the central metal,the type and number of the ligands,and structural dimensions are identical,but only coordination mode of pda is different.This leads to the different the crystal density(Dcal)(D7>D8),which indicates that the packing of(7)is closer than that of(8).In SPS and FISPS,response bands of(7)are broaden to the visible region,compared to those of(8).