Jian-Sheng Wu

Ion-pair complexes with strong near infrared absorbance: Syntheses, crystal structures and spectroscopic properties

Three ion-pair complexes, [4-NH(2)-Py](2)[M(mnt)(2)] (4-NH(2)-Py(1+)=4-amino-pyridinium; mnt(2-)=maleonitriledithiolate; M=Pt (1), Pd (2) or Ni (3)), have been synthesized and characterized. In the crystal of 1, the strong H-bonding interaction was found from the protonated N-atom of pyridinium to the CN group of [Pt(mnt)(2)](2-) together with a weak Pt...H interaction between the anion and the cation. The crystals of 2 and 3 are isostructural with very similar lattice parameters and packing structures, which are distinct from the crystal of 1. Two kinds of strong H-bonding interactions are observed in the crystals of 2 and 3 between the CN groups of [M(mnt)(2)](2-) anion and the protonated N-atom of 4-NH(2)-Py(1+) cation as well as the CN groups of [M(mnt)(2)](2-) anion and the amino group of 4-NH(2)-Py(1+) cation. Complex 1 shows an intense near-IR absorbance in acetonitrile and solid state, such an absorption band is probably assigned to IPCT transition as well as a trace amount of [Pt(mnt)(2)](1-) species; complex 3 possesses a weak near-IR absorption band which can be attributed to the mixture of d-d transition in [Ni(mnt)(2)](2-) and IPCT transition as well as a trace amount of [Ni(mnt)(2)](1-) species.

Chemical In Situ Polymerization of Polypyrrole Nanoparticles on the Hydrophilic/Hydrophobic Surface of SiO2 Substrates

Polypyrrole (PPy) nanoparticles formed by chemical in situ polymerization were deposited on the hydrophilic/hydrophobic surface of SiO2 substrates to give the diversely morphology, respectively. The morphologies of PPy nanoparticles deposit were investigated using optical microscope, scanning electron microscope (SEM), and atomic force microscope (AFM) imaging techniques. The morphology of Y- and T-shape wrinkles was observed on the hydrophilic surface of SiO2 substrate, while the morphology of polygon-shape wrinkles on the hydrophobic surface of SiO2 substrate, and this distinction is due to the difference of the surface energy between the hydrophilic and hydrophobic surface of SiO2 substrate and so-called “memory effect.”

Syntheses, Crystal Structures, and Spectroscopic Properties of Two Ion-Pair Charge Transfer Compounds Containing Bis(maleonitriledithiolato) Platinum/Palladium(II) Anion and Substituted Benzylpyridinium

Two ion-pair charge-transfer compounds, [CNBzNH2Py]2[ M(mnt)2]·MeCN (CNBzNH2Py+ = 1-(4’-cyanobenzyl)-4-aminopyridinium; mnt2− = maleonitriledithiolate; M=Pt (1), Pd (2)), have been synthesized and characterized. The x-ray single-crystal studies revealed that both of the crystals crystallize in the monoclinic space group P21/c with an asymmetric unit containing one [CNBzNH2Py]+ cation and a half of the [M(mnt)2]2− anion together with one MeCN molecular; there is no evident change of the crystal system, and the dihedral angles between the phenyl and pyridine rings and the N3/C10/C11 reference plane of the cation, as well as the stacking modes of the anions and the cations, when the metal ion is changed from Pt(II) to Pd(II). There exist π…π interactions between the neighboring benzene ring and CN group of the cations, as well as H-bonding interactions between the CN group of the MeCN molecular and the NH2 group of the cation in both of the compounds. Ultraviolet/visible (UV-vis) spectrum studies disclosed that these show different absorption bands in the UV-vis regions.