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Some inner C-cyanation and C-alkylation complexes have been described. Reactions of 2-N-substituted N-confused tetraphenylporphyrin (2-NCH2YNCTPPH) with Co(SCN)2 afford C-alkylation (14) and C-cyanation (15–17) complexes. The crystal structures for the inner C-alkylation product of thiocyanato(2-aza-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-benzyl-21-carbaporphyrinato-N,N′,N″)cobalt(II)·0.5 octane solvate [Co(2-NCH2-p-CH3C6H4-21-CH2C6H5NCTPP)(NCS)·0.5C8H18; 14·0.5C8H18] and the inner C-cyanation products of thiocyanato(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II) [Co(2-NCH2COOCH2CH3-21-CN NCTPP) (NCS); 15], thiocyanato(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II)[Co(2-NCH3-21-CNNCTPP) (NCS); 16], and thiocyanato(2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-cyano-21-carbaporphyrinato-N,N′,N″)cobalt(II) [Co(2-NCH2C6H5-21-CNNCTPP) (NCS); 17] have been reported. The geometry around Co2+ ion in these four complexes is a distorted tetrahedron with a C2v symmetry. Two possible mechanisms were proposed to explain the formation of inner C-alkylation (14·0.5C8H18) versus C-cyanation (15–17) products in these complexes with an axial *NCS− ligand.

Two experimentally well characterized four-coordinate complexes of the general formula [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)L] (with L = Cl− and N*CS− for 3 and 4) are considered for this study. The crystal structures of the paramagnetic chloro(2-aza-2-[p-methyl benzyl]-5,10,15,20-tetraphenyl-21-m-xylyl-21-carbaporphyrinato-N,N′,N″) cobalt(II) octane solvate [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)Cl]·0.5C8H18 (3·0.5 C8H18) and thiocyanato-N-(2-aza-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-m-xylyl-21-carbaporphyrinato-N,N′,N″) cobalt(II) [Co(2-NCH2-p-C6H4CH3-21-m-CH2C6H4CH3NCTPP)(NCS)] (4) were established. The geometry around the Co2+ ion in 3·0.5 C8H18 (or 4) is a distorted tetrahedron, with C2v symmetry. The magnitude of the zero-field splitting (ZFS) parameter (D) was reported to change from 44.5 cm−1 in 3 to 30.0 cm−1 in 4 through DC magnetic susceptibility determinations. The |D| value can be related to the magnitude of the ligand-field splitting parameter of the axial k-donating Cl− ligand of 3 and the axial π-accepting NCS− ligand of 4 at the cobalt sites.

Piezoelectric energy harvesting is a promising technique for scavenging ambient mechanical motion for driving compact, low-power, multi-functional electronic devices. To adapt to various ambient surroundings, the geometric configurations and sizes varied in wide ranges with high operational reliabilities and piezoelectric performance have been regarded as a key for piezoelectric harvester design. Herein, by applying a normal force, we report an innovative structure for harvesting electric energy from bending the obliquely aligned GaN piezoelectric nanorods (NRs) that are integrated in the vertically integrated nanogenerator (VING). The single-crystalline GaN NRs used here were successfully synthesized with obliquely alignments on the pyramided Si substrate by plasma-assisted molecular beam epitaxy (PA-MBE). Using conductive atomic force microscope (c-AFM), a remarkable change in the Schottky barrier height (SBH) between the tip and GaN NR is observed upon bending an oblique-aligned GaN NR. This demonstrates that a remarkably enhanced piezoelectric performance of GaN NRs can be achieved by coupling a lateral force. We anticipate that this work will provide an efficient approach for coupling the lateral loading to enhance the electric potential in piezoelectric NRs-embedded VING, and thus open a new path for efficiently generating electric energy.

The crystal structures of 2-aza-2-[p-(isopropyl)benzyl]-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″)palladium(II) [Pd (2-NCH2-p-C6H4-isoC3H7NCTPP); 3], (2-azo-2-[p-(isopropyl)]-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″)platinum(II) [Pt(2-NCH2-p-C6H4-isoC3H7NCTPP); 4], iodo(2-azo-2-[p-(isopropyl)benzyl]-5,10,15,20-tetraphenyl-21-hydrogen-21-carbaporphyrinato-N,N′,N″)mercury(II) toluene solvate [Hg(2-NCH2-p-C6H4-isoC3H7-21-H-NCTPP)I⋅C6H5CH3; 5⋅C6H5CH3], (2-azo-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″)nickel(II) [Ni(2-NCH2-p-C6H4-CH3NCTPP); 6] and iodo(2-azo-2-[p-methylbenzyl]-5,10,15,20-tetraphenyl-21-hydrogen-21-carbaporphyrinato-N,N′,N″)mercury(II) [Hg(2-NCH2-p-C6H4-CH3-21-H-NCTPP)I; 7] were determined. The coordination sphere around the Pd2+ (or Pt2+, Ni2+) ion in 3 (or 4, 6) is distorted square planar (DSP) whereas for Hg2+ in 5 (or 7), it is a distorted tetrahedral complex with the T-based pyramid of the C2v symmetry. The coupling of H(17) in 5 (7) to 199Hg with J [199Hg–H(17)] = 34.8 Hz (5) and J [199Hg–H(17)] = 34.2 Hz (7), supported the assignment of agostic η2–C–H(17)⋯Hg interactions in these two mercury complexes.

In the past few decades, gate insulators with a high dielectric constant (high-k dielectric) enabling a physically thick but dielectrically thin insulating layer, have been used to replace traditional SiOx insulator and to ensure continuous downscaling of Si-based transistor technology. However, due to the non-silicon derivative natures of the high-k metal oxides, transport properties in these dielectrics are still limited by various structural defects on the hetero-interfaces and inside the dielectrics. Here, we show that another insulating silicon compound, amorphous silicon nitride (a-Si3N4), is a promising candidate of effective electrical insulator for use as a high-k dielectric. We have examined a-Si3N4 deposited using the plasma-assisted atomic beam deposition (PA-ABD) technique in an ultra-high vacuum (UHV) environment and demonstrated the absence of defect-related luminescence; it was also found that the electronic structure across the a-Si3N4/Si heterojunction approaches the intrinsic limit, which exhibits large band gap energy and valence band offset. We demonstrate that charge transport properties in the metal/a-Si3N4/Si (MNS) structures approach defect-free limits with a large breakdown field and a low leakage current. Using PA-ABD, our results suggest a general strategy to markedly improve the performance of gate dielectric using a nearly defect-free insulator.

Hexavalent Cr has been identified as one of the toxic metals commonly present in industrial effluents. Among the treatment techniques developed for removing Cr(VI) from waste waters, sorption is most commonly applied, due to its simplicity and efficiency. However, few adsorbents can be recycled and reused cost-effectively. In this study, the removal and recovery of Cr(VI) from water using Li/Al LDH was investigated. The removal of Cr(VI) by Li/Al LDH was evaluated in a batch mode. The results demonstrated that Cr(VI) adsorption onto Li/Al LDH occurs by replacing the Cl− that originally exists in the interlayer of the adsorbent. The degree of Cr(VI) adsorption observed for Li/Al LDH was relatively high and the process occurred rapidly; however, a portion of adsorbed Cr(VI) was gradually desorbed, due to the Li de-intercalation of Li/Al LDH. Lithium de-intercalation from Li/Al LDH with interlayer Cl− and interlayer Cr(VI) follows the first order kinetics and has the activation energies of 76.6 and 41.5 kJ mol−1, respectively. The properties of thermal unstablility and the high adsorption capacity of Li/Al LDH may lead to the development of an innovative technique for the removal of Cr(VI) from Cr(VI)-containing wastewater. That is, Li/Al LDH may be used as an effective adsorbent for the adsorption of Cr(VI) in an ambient environment. Following the adsorptive process, the adsorbed Cr(VI) may be released, using heated water to treat the Cr(VI)-containing Li/Al LDH particles. Through this hydrothermal treatment of the used adsorbent, Cr(VI) can be recovered and the solid product (gibbsite) can be recycled for further use.