Synthesis,Charactrization And Theoretical Calculation Of Copper(â… ) Complexs With N-heterocyclic Chelating Ligand

Copper(I) complexes have received much interest from the scientific researchers all over the world, due to the low cost, diverse structure, particular photochemical and photophysical properties, and promising applications in optoelectronic devices, optical sensors, solar energy conversion, and nonlinear optics. In this thesis, two kinds of N-heterocylic chelating ligands have been designed and synthesized, one is the bipyridyl-based ligands containing the ester: 6-methoxycarbonyl-2,2′-bipyridine(bpym) and 6-methoxy-carbonyl-4,4′-dimethyl-2,2′-bi- pyridine(mbpym); the other is the pyrimidyl triazole chelating ligand, 3-tert-butyl- 5-(pyrimidine-2-yl)-1H-1,2,4-triazole(bmptz H). Using two kinds of N-heterocylic chelating ligand above mentioned, we have prepared six mononuclear Cu(I) complexes. Their structures and photophysical properties have been analyzed and investigated by single-crystal X-ray diffraction, ultraviolet-visible absorption spectrum, infrared spectrum, fluorescence spectrum, elemental analysis, and nuclear magnetic resonance spectroscopy.Three mononuclear Cu(I) bipyridyl complexes containing the ester, [Cu(bypm)(PPh3)2](Cl O4)(1), [Cu(mbypm)(PPh3)2](Cl O4)(2) and [Cu(bypm)(dppb)](Cl O4)(3), have been synthesized by utilizing the N-heterocylic chelating ligands bpym and mbpym. X-ray single-crystal diffraction shows that the Cu(I) atom of each complex is bound to two N atoms from bpym or mbpym and two P atoms from triphenylphosphine to form an N2P2 distorted tetrahedral geometry, and the ester group doesn’t coordinate to the Cu(I) atom. Owing to the effect of the substituents and phosphine ancillary ligand, the dihedral angles between two pyridyl rings follow a ranking of 1(4.640o) < 2(av. 9.065o) < 3(15.648o), while a reverse order lies in the dihedral angles between the methoxycarbonyl and its conjoined pyridyl ring(1(15.224o) > 2(av. 8.983o) > 3(2.786o)). Complexes 1–3 show a weak low-energy absorption band at 330–500 nm in CH2Cl2 solution, ascribed to charge-transfer transitions with appreciable 1MLCT character, as supported by TD-DFT calculations. The solid-state luminescence is observed in 1–3 at room temperature, which is affected by the phosphine ancillary ligand, the substituents on the 2,2′-bipyridyl, Cu…Ocarbonyl separation, and the above-mentioned dihedral angles.Three mononuclear Cu(I) halide, Cu(bmptz H)(PPh3)X(X = I(4);Br(5);Cl(6)) have been synthesized by using the bis-chelating ligand bmptz H. Single-crystal structural analysis shows, that each copper(I) atom is bound to N1 and N5 atoms of bmptz H, one halogen atom, and one P atom of triphenylphosphine to form an N2 PX distorted tetrahedral geometry, consistent with two theoretical calculation results of Cu(I) complex 4. A comparatively weak low-energy absorption band is observed at 320–450 nm in CH2Cl2 solution at room temperature for 4–6, ascribed to charge-transfer transitions with appreciable 1MLCT character. Complexes 4–6 are non-emissive in fluid solutions, whereas they have good luminescence properties in solid states at ambient temperature. The solid-state emission are in the order 4 < 5 <6, consistent with that of the ligand filed strength of the halide(I￣ < Br￣ < Cl￣), most likely originating from the 3MLCT and 3XLCT transitions.