Group 12 and silver(I) tetramethyl-m-benziporphodimethene (TMBPDM) complexes with phenyl, methylbenzoate, or nitrophenyl groups as meso substituents were synthesized and fully characterized. The dimeric silver(I) complex displays an unusual η(2),π coordination from the β-pyrrolic C=C bond to the silver ion. All of the complexes displayed a close contact between the metal ion and the inner C(22)-H(22) on the m-phenylene ring. The downfield chemical shifts of H(22) and large coupling constants between Cd(II) and H(22) strongly support the presence of an agostic interaction between the metal ion and inner C(22)-H(22). Crystal structures revealed that the syn form is the predominant conformation for TMBPDM complexes. This is distinctively different from the exclusive anti conformation observed in m-benziporphyrin and tetraphenyl-m-benziporphodimethene (TPBPDM) complexes. Evidently, intramolecular hydrogen-bonding interactions between axial chloride and methyl groups stabilize syn conformations. Unlike the merely syn conformation observed in the solid-state structures of TMBPDM complexes that contain an axial chloride, in solution these complexes display highly solvent- and temperature-dependent syn/anti ratio changes. The observation of dynamic (1)H NMR spectroscopic scrambling between syn and anti conformations from the titration of chloride ion into the solution of the TMBPDM complex suggests that axial ligand exchange is a likely pathway for the conversion between syn and anti forms. Theoretical calculations revealed that intermolecular hydrogen-bonding interactions between the axial chloride and CHCl(3) stabilizes the anti conformation, which explains the increased ratio for the anti form when dichloromethane or chloroform was used as the solvent.

The structure of a bi - Cd organic complex [ Cd 2(bis(2-pyridyl)formamine)3 or 1], is analyzed thoroughly by 1 H and 113/111 Cd NMR in solution. Only one representative set of pyridyl proton resonance of a total of six pyridines in 1 was observed. The resonance of protons in pyridine ring can be assigned by both 2D COSY and 2D NOESY. Similarly, only one Cd (either 113 Cd or 111 Cd NMR signal was observed too. This indicates that the two Cd atoms in 1 are chemically equivalent. The Cd signal is split by its three neighboring equivalent protons on the bridged carbon atoms ( C a H )3, resulting in a quartet. The 3 J 113 Cd –1 H and 3 J 111 Cd –1 H are 44 and 42 Hz, respectively, measured directly from the spectral pattern. The proton NMR signals of C a H composed from three sources: (1) superimposed doublets arising from Cd – H –113 Cd and Cd – H –111 Cd ; (2) a pseudo triplet from 113 Cd – H –113 Cd , 111 Cd – H –111 Cd and 113 Cd – H –111 Cd and (3) a singlet from those H's surrounded by all non-magnetic Cd atoms. They superimpose and appear as a quintet with intensity ratio of 1:12:38:12:1, explainable by the above constituents and their associated Cd – H splitting analyses. We deduced that the three bis(2-pyridyl)formamidine groups have a three-fold symmetry with respect to the Cd – Cd axis, i.e., the three bis(2-pyridyl)formamidine units are co-planar and spaced 120 degrees from each other based on above observations. This implies the key C a atom exists as a hybrid of two canonical forms (– N = C a H – N – ↔ – N – C a H = N –). As a consequence, 1 does not exhibit chirality. We exemplified that Cd NMR study is well suited for investigating those metalloproteins if the calcium and/or zinc ions contained can be replaced by 113 Cd /111 Cd ions of similar size.

The switching current of the PZT domain patterns was detected by the conductive atomic force microscopy. The impact of the scan rate on the current contrast was studied. Successive current images of domain evolution during the polarization switching process were obtained. The impact of the local force exerted by the tip and the polarization cycles of the patterns were studied. The results suggested that the compressive strain exerted by the tip can decrease the piezoelectric coercive field and the polarization fatigue can increase the piezoelectric coercive field in the polarization inversion process from bottom to top.

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