Synthesis And Application Of Soluble Phenylethynyl Copper(?) Derivatives With Hydrophilic Side Chains

As early as the 1980 s,copper organoacetylides(COA)had been widely studied by scientists as a sort of P-type semiconductor.Especially copper phenylacetylide and its derivatives had been used as photo-electronic materials.However,most COAs are insoluble and infusible polymer powders except those with bulky substituents.It is difficult to prepare a uniform and ultra-thin film by spin-coating or vapor deposition.In this paper,we have designed two phenylacetylene derivatives with hydrophilic side chains and have successfully prepared two soluble yne-copper compounds by a new polymerization method.Then we have fabricated the COA film devices by spin-coating and further have tested their photo-electronic properties.First,we have synthesized two phenylacetylene ligands L1-L2 with para-substituted hydrophilic chains with different lengths.The two ligands and equivalent monovalent copper salts were polymerized in chloroform with triethylamine as base,respectively,to give two hydrophilic copper(I)phenylacetylide derivatives CuL1-CuL2.Moreover,they are fully characterized by infrared spectrum,ultraviolet visible absorption spectrum,X-ray photoelectron spectroscopy,X-ray diffraction spectrum,elemental analysis and inductively coupled plasma-emission spectroscopy.The valence of copper and the coordination mode of copper-yne were determined.Both polymers are soluble in some organic solvents containing chlorine,and their weight-average molecular weights can reach 100,000.Second,we have chosen the chloroform/1,1,2-trichloroethane mixed solvent with the volumetric ratio of 4/1 to dissolve the yne-copper polymers.The uniform and transparent copper acetylide films with the thickness of about 350 nm were fabricated by spin-coating method on glass plate,and further the comb-like Au electrodes were deposited on polymer film surface.The simple voltage-current tests showed that two polymers have evident semiconductor characteristics.Especially,the conductivities of two films were greatly improved after annealed at 70 °C for 10 minutes.These film devices only showed weak photoconductivity under the irradiation of 470 nm monochromatic light.Finally,we have found that the conductivities of hydrophilic phenylacetylide copper films can respond to hydrogen chloride gas.The conductivity of film CuL1 can increase by more than two orders of magnitude after hydrogen chloride gas treatment,while that of film CuL2 is only improved less than 5 times.The absorption spectra and colors of both polymers were evidently changed under the gas atmosphere of HCl.These properties can potentially be used for the optical/electric dual detection for hydrogen chloride gas.