The Application And Crystal Structure Research Of Acyl Thiourea And Its Transition Metal Complexes

Acyl thiourea derivatives have been widely used as ligands in coordination chemistry,the transition metal ions react with acyl thiourea ligands to form complexes,polymers and clusters with different structures.The acyl thiourea transition metal complex is one of the hot spots in th e field of inorganic chemistry because of its wide application value in the design and research of biosensors,industrial catalysts and new material precursors.In this paper,a series o f transition metal complexes containing 1-（acyl/aryl）-3-（mono/di-substituted）thiourea were synthesized,and their crystal structures and properties are studied,as well as the application of acyl thiourea to identify transition metal ions.The main work includes the following aspects:1.Seven 1-（acyl/aryl）-3-（mono/di-substituted）thiourea derivatives were synthesized by using low boiling point dichloromethane（CH₂Cl₂）as solvent,adding appropriate amount of phase transfer catalyst PEG-400,and reacting directly with differ ent amine compounds without separati ng the intermediate acyl isothiocyanate.The structures of the corresponding compounds were characterized by ¹H NMR.The ion recognition and sensing properties of the different N-substituted acyl thioureas were investigated by UV-Vis and fluorescence spectroscopy in organic media upon the addition of metal ion.Ultraviolet-visible spectra of N-substituted acyl thiourea show that there is an absorption band at 281 nm,which is the characteristic absorption peak of C=S,and the addition of Cu（Ⅱ）makes the absorption band redshift to 304 nm.At the same time,a new absorption band appears at 450-500 nm,which is caused by metal-ligand charge transfer（MLCT）.This indicates that acyl thiourea has a coordination reaction with Cu（Ⅱ）.The fluorescence spectra of N-substituted acyl thiourea showed that the fluorescence intensity of the solution was significantly enhanced only when Cu（Ⅱ）was added.2.A diacyldithiourea derivative was prepared by ultrasonic-assisted method and"two-step,one-pot"synthesis method.The structure of the single crystal was determined by X-ray diffraction.The intermolecular and intramolecular hydrogen bond interactions were found in the compound.The results obtained by ¹H NMR,¹³C NMR and FT-IR were consistent with the target product.The crystal structure was analyzed by Hirshfeld surface analysis and 2D fingerprint analysis.The interaction of H???H bond accounted for 36.6%,which contributed the most to the whole intermolecular hydrogen bond.There is aΠ???Πinteraction between two adjacent molecules,which is self-assembled into a supramolecular chain structure by hydrogen bonding.The complexation ability of diacyldithiourea derivatives to different metal ions was investigated by UV-Vis and fluorescence spectra.UV-Vis spectra show that the compound reacts selectively with Cu（Ⅱ）,which is accompanied by the breaking of the C=O and C=S bonds.By comparison of infrared spectra,it is found that the peak shape of C=O and C=S functional groups changes after interaction with Cu（Ⅱ）ions,and it is speculated that C=O and C=S form C-O-Cu and C-S-Cu structures after interaction with Cu（Ⅱ）ions.3.Two di[N,N-diethyl-N’-p-nitrobenzoylthiourea]Platinum（Ⅱ）and Palladium（Ⅱ）complexes have been synthesized.The crystal structure of the complexes was determined by X-ray single crystal diffraction.Both complexes belong to monoclinic space group P21/c.The two deprotonated ligands act as bidentate chelators in complex and coordinated with Pt（Ⅱ）/Pd（Ⅱ）central ions through one S atom and one O atom,which are in a cis-butterfly structure.Hirshfeld surface analysis and 2D fingerprint analysis of the crystal structure of the complex indicate that the H???H interaction is an important interaction for the formation of strong hydrogen bonds.The crystal structure of the Pt（Ⅱ）/Pd（Ⅱ）complex is different from that reported in the literature.In both structures,a small solvent molecule of dichloromethane is present,which is connected to the complex by C-H???Cl intermolecular hydrogen bonding.Fluorescence spectra showed that both ligands and complexes had good fluorescence properties,and the coordination could enhance the fluorescence intensity.4.Two di[N-ethoxycarbonyl-N’-3/4-methyl-phenyl-thiourea]Palladium（Ⅱ）complexes were synthesized and their crystal structures were obtained by solvent volatilization method.The single crystal structures were determined by X-ray single crystal diffraction.In the complex,the anionic thiourea ligand is chelated with Pd（Ⅱ）ions by S-and N-donor atoms to form an ideal quaternary 1,3-S,N chelating ring structure,with trans-S-Pd-S and trans-N-Pd-N bond Angle of 180°,both complexes are trans Z configurations.The coordination mode of this complex is different from that previously reported,and this configuration is easier to form intermolecular hydrogen bonds,thus making the crystal structure of the two complexes more stable.According to Hirshfeld surface analysis and 2D fingerprinting point,the interaction and proportion of H???H,C-H???H-C,O???H/H???O,S???H/H???S,and N???H/H???N were observed in the two Pd（Ⅱ）complexes,and H???H has the largest interaction proportion.At the same time,the fluorescence spectra showed that the fluorescence intensity of the complex decreased slightly after the coordination,indicating that the coordination of the ligand with Pd（Ⅱ）ions made it tend to form more stable complexes.