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In order to study the electronic structure and structural stability of borane [ABSTRACT FROM AUTHOR]

For the structure interpretation and rationalization of boranes and borane analog compounds, the five C symmetric molecules BH, AlH, GaH, SiH, and GeH are proposed as the structural units for the construction of the boranes and borane analog compounds AlH, AlH, GaH, Si, and Ge. The superiorities of the structure interpretation method can be summarized as following. Firstly, the three kinds of hydrogens, i.e., endo-, bridge-, and external-hydrogen of the boranes and borane analog compounds can be regarded as inherited from the corresponding structural units BH, AlH, and GaH. Secondly, the arcuated skeleton of the boranes and borane analog compounds can be considered as originated from the dihedral angle of the corresponding structural units BH, AlH, GaH, SiH, and GeH. Thirdly, the five structural units BH, AlH, GaH, SiH, and GeH, and their iso-electronic molecule CH can act as a linkage among the boranes, borane analog compounds, and hydrocarbon compounds on some extent. Fourthly, the instability of some boranes can be correlated with the structure constraint of the BH structural unit within the constructed borane. All computational work is performed at B3LYP/6-311+G(D) level. [ABSTRACT FROM AUTHOR]

The closo-boranes BH (6 ≤ n ≤ 12) have been constructed topologically by fusing together of the two component nido-boranes BH and BH. The stability and aromaticity of the closo-boranes can be regarded as inherited from the two component nido-boranes, and the closo-boranes which can be formed by two same nido-boranes through sharing a 'ring' fragment or without sharing any BH fragment are more stable than other types of closo-boranes. It can be anticipated that the constructing method of this article can bring enlightment to the structural interpretation process of other systems. [ABSTRACT FROM AUTHOR]

The electronic structure of the butterfly-shaped arachno-borane BH is rationalized by the octet rule in comparison with its butterfly-shaped isoelectronic species CH. The computational results of geometry and molecular orbital (MO) graphs are compared between the two isoelectronic species. And the point group method is employed to describe the MO correlation between the hydrogen-bridged molecule BH and the hypothetical molecule BH. The results indicate that the electronic structure of arachno-borane BH can be rationalized by the octet rule constrast with its isoelectronic hydrocarbon counterpart CH. And the MO description on the electronic structure of hydrogen-bridge bonds in BH is provided through the point group treatment of a hypothetical reaction. All the computational work are performed at MP/6-31++G(d, p) level. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical analyses of the behavior with chain length of the static first hyperpolarizabilities for a series of all-trans polysilaacetylene (PSA) oligomers with identical R-terminal groups at each end have been performed by using high-accuracy ab initio quantum mechanics method (MP2/6-31+G∗). Moreover, 15 R groups have been assessed to study the substituting effect on the β values. Our results indicate that these R–(SiHalic> n –R oligomers represent the character similar to that of the conventional push–pull chromophores. Besides, for some substituted PSA chromophores, to further increase the conjugated chain length could not effectively affect the β values because the first hyperpolarizabilities reach the saturated values. The evolution of the first hyperpolarizability per unit cell (β/n) reveals that the R substituents strongly affect β for short oligomers but have a limit influence on β for long chains. More importantly, the chain-end asymmetry plays a key role to contribute to β for these substituted PSA oligomers. On the other hand, it also shows that the bond length alternation (Δr) can be used to roughly estimate the relative magnitudes of β among the different R-terminal substituted PSA oligomers. [Copyright &y& Elsevier]

A triphenylamine derivative (E)-N,N-diphenyl-4-(2-(pyridin-2-yl)vinyl)benzenamine (L) was synthesized, and the corresponding cadmium complex CdI 2 L 2 crystal was obtained and solved by single crystal X-ray diffraction analysis. The experimental resutls of one photon absorption (OPA) and one photon excited fluorescence (OPEF) indicate that coordination of CdI 2 only has slight effect on the spectrum peak position relative to the free ligand. Besides the Stokes shift, the full width half maximum of OPEF and the variation of the "peak span between solvents" from OPA to OPEF can also indicate the electron transition direction of the excitation process. The laser experiments show that both the ligand and complex have considerable two photon excited fluorescence (TPEF) emission. The experimental Stokes shift is correlated with the computational solvent polarity rMPI, and the results illustrate that the curve of "experimental Stokes shift vs. solvent rMPI" is exactly the Boltzmann S-curve. The computational results also indicate that the static interaction between the CdI 2 L 2 molecules in crystal has strong effect on OPA properties. Considering the weak coordination bond strength of the complex CdI 2 L 2 , the S1→S0′ fluorescence emission may occur on both ligands, although the S0→S1′ excitation only occurs on the right ligand. A fluorescent complex was prepared. It exhibits superior one- and two-photon excited fluorescence. The curve of "experimental Stokes shift vs. computational solvent polarity rMPI (in unit of kcal/mol)" is exactly the Boltzmann S-curve. [Display omitted] • The complex has excellent one- and two-photon excited fluorescence. • The "experimental Stokes shift vs. solvent polarity" is exactly the Boltzmann S-curve. • The geometry distortion of the complex is explained by computational method. • The OPA mechanism of complex is interpreted by hole-electron method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exploring the influences of F− and OH− ligands on dimerization and dissociation in weakly acidic solutions. • The transition of terminal F to bridging F. • The effect of anion on the stability of dimers formed in strongly alkaline conditions once crystallization. Dimerization mechanism of aluminum species is investigated in weakly acidic solutions and in strongly alkaline solutions using density functional theory, respectively. The results indicate the dimerization is controlled by dehydration of monomeric aluminum and the dissolution of dimer is controlled by the hydroxyl bridge cleavage in weakly acidic solutions. The two processes are enhanced by the rising pH. In addition, the main pathway generating the fluorine bridge is not the direct polymerization, but the terminal substitution of F− into polymeric aluminum followed by the transition of terminal F to bridging F. The formation of fluorine bridge promotes dissolution and di-fluorine-bridged dimer should be excluded. In strongly alkaline solutions, the formation processes of three dimers were speculated, and the existence of mono-hydroxyl-bridged dimer is denied due to the extraordinary instability and high formation energy barriers. It is possible that mono-oxygen-bridged and di-hydroxyl-bridged dimers coexist in highly alkaline solutions. However, the salts of mono-oxygen-bridged anion are much more stable than salts of di-hydroxyl-bridged anion due to the effect of counter cations and the removal of ambient water molecules. [ABSTRACT FROM AUTHOR]

In order to elucidate the electronic structure of the hydrogen-bridge bond in BH molecule, the formation process of BH had been created by a hypothetical reaction of 'BH + 2H', and the symmetry principles for reaction are applied in the process of creating new molecular orbitals through linear combination of the old orbitals. The orbital components of the hydrogen-bridge bond in BH are obtained, and the electronic structure of the hydrogen-bridge bond is explained qualitatively. In addition, the idea that explains the structure of a molecule by creating a hypothetical reaction is proposed, which might make more application in other cases. [ABSTRACT FROM AUTHOR]

The metal-organic hybrid complex HgI 2 L (L = 4'-{4-[4-(N,N-dipropylamino)styryl]phenyl}6-phenyl-2,2′-bipyridine) was synthesized by coordination of L with HgI 2. The crystals of HgI 2 L were obtained by self-assemble of HgI 2 with L under ambient conditions, and its structure has been solved by single crystal X-ray diffraction. The fluorescence emission spectrum experiment shows that the complex has remarkable strong one and two-photon excited fluorescence. To clarify the mechanism of strong fluorescence properties, the natural transition orbitals (NTOs) and hole-electron transition analysis ground on the computational results under state specific PCM/TD-CAM-B3LYP method was performed. The results illustrate that, there is high similarity between the electronic structures and geometries of the optimized S0 and S1, and the high similarity is benefit to decreasing the non-radiative energy dissipation during geometry reorganization under S1 state, which is helpful in increasing the fluorescence intensity. In addition, the appreciable overlap between electron donor NTO and electron acceptor NTO in S1 state induce to the large oscillator strength of deexcitation, which also attribute to the strong fluorescence. Image 1 • A novel fluorescent complex was easily prepared. • It exhibits superior one- and two-photon excited fluorescence. • It has high fluorescence quantum yield and large two-photon absorption cross-section. • Its ground state and first excited state have high geometry similarity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A metal‐free, green, and sustainable functionalization of unactivated alkyl sp3 C—H bonds is reported using iodine(III) as a feasible dehydrogenation agent under visible light or KBr, and alkyl chlorides, bromides, alcohols, and ketones could be constructed by addition of different coupling reagents. Cheap and safe iodobenzene diacetate was used to form a radical to activate the alkyl sp3 C—H bond in a highly efficient manner, which can construct different alkylation products by adding corresponding coupling reagents. [ABSTRACT FROM AUTHOR]

Two-photon excited fluorescence (TPEF) is widely sought after in bioimaging applications due to its exceptional deep tissue penetration and excellent high spatiotemporal resolution. In this paper, benzothiazole and benzimidazole are linked to N, N-diphenylaniline, respectively, through pyridine vinyl. Two new D-π-A (electron donor-π conjugated bridges-electron acceptor) probes (P1, P2) were designed and synthesized. The molecular structures were completely characterized through FT-IR, 1H NMR, 13C NMR, ESI-MS, and X-ray single crystal diffraction. The probes have good one-photon excited fluorescence and two-photon excited fluorescence. Experimental test results indicate that they can be fluorescence probes for biological imaging of HePG2 and juvenile zebrafish. In addition, the fluorescent probes also have the ability to target and locate cancer cell mitochondria. [Display omitted] • The two-photon absorption cross sections of P1 and P2 are up to 1468 and 1263 GM, respectively. • The probes exhibit good optical performance and mitochondrial localization. • P1 and P2 fluorescent probes have low biological toxicity and can be used for in vivo biological imaging. [ABSTRACT FROM AUTHOR]

Two novel D-π-A-π-D structural 2,2 ′ -bipyridine derivatives based on different electron donors, namely aza-crown ether and triphenylamine groups were synthesized and characterized. One of which was characterized by single crystal X-ray diffraction determination. Their linear photophysical properties were systematically investigated in various solvents. The two-photon excited fluorescence were investigated. The two dyes both exhibited excellent one- and two-photon excited fluorescence as well as high quantum yield and large two-photon absorption cross-section ( δ ). Fluorescence microscopy imaging of them in NIH/3T3 cell line was studied. The result indicated that both of them exhibit excellent biological compatibility. [ABSTRACT FROM AUTHOR]

An electron donor-π-bridge-electron acceptor (D-π-A) structural optical functional organic ligand ( L ) comprising a triphenylamine moiety as the electron donor and pyridine moiety as the electron acceptor was synthesized. By self-assembly of L with ZnBr 2 and ZnI 2 in methanol and dichloromethane, two fluorescent Zinc(II) complexes ZnBr 2 L 2 ( 1 ) and ZnI 2 L 2 ( 2 ) were obtained. The structures of 1 and 2 were solved by single crystal X-ray diffraction analysis. Study of nonlinear optical properties has shown that the complexes exhibit excellent two-photon excited fluorescence with the two-photon absorption cross-section values of 516 GM for 1 and 501 GM for 2 . The structure-property relationships were detailed through X-ray crystallography. Results of living cell imaging experiments show the potential of them in fluorescence microscopy bioimaging. [ABSTRACT FROM AUTHOR]

A new fluorescent material was prepared by complexation of a D-π-A structural organic ligand with ZnBr2. The material exhibits good one- and two-photon excited fluorescence. One- and two-photon fluorescence imaging shows that HepG2 cytoplasm can be labeled by the fluorescent material. The results show that the material has great potential in fluorescence microscope imaging. [Display omitted] • A new material with zinc ion and π-conjugated organic ligands has been synthesized. • The complex shows good one- and two-photon excited fluorescence. • The material shows the value in fluorescence microscopy bioimaging application. • The experimental correlation between the solvent polarity and the Stokes displacement is described by the Boltzmann fitting method. A luminescent material with various optical properties based on a triphenylamine Zn(II) complex is described. The ultraviolet–visible absorption, one-photon excited fluorescence (OPEF) and two-photon excited fluorescence (TPEF) of the complex indicate that the material has good OPEF and TPEF properties. And the results of one- and two-photon HepG2 cells imaging experiments show the potential of the complex in fluorescence microscopy bioimaging. The experimental Stokes shift and the FWHM (full-width at half-maximum) in different solvents were correlated with the rMPI polarity of the solvent, and the perfect Boltzmann curves were obtained, where the Boltzmann correlation between Stokes shift and solvent polarity is reported for the second time. But the Boltzmann correlation between FWHM and solvent polarity is reported for the first time. In addition, the computational results indicate that, the covalent bond within the salt ZnBr 2 is strengthened by the coordination, and the newly formed coordination bond Zn-N is stronger than the original covalent bond Zn-Br. [ABSTRACT FROM AUTHOR]

Based on the chelation of 6-phenyl-4′-(4-[4-(diphenylamino)styryl]phenyl)-2,2′-bipyridine ( L ) to Hg(II) ions, two luminescent coordination complexes HgBr 2 L ( 1 ) and HgI 2 L ( 2 ) were prepared. Compared with the free ligand, the complexes exhibit enhanced two-photon excited fluorescence and larger two-photon absorption cross-section values. Time-dependent density functional theory calculations were carried to investigate the influence of central metal ion on the characteristic of charge transition of the complexes. The results indicated that the complexation of the ligand with Hg(II) ion causes stronger intramolecular charge transfer, leading to enhanced two-photon absorption of the complexes. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of two thiosemicarbazide and semicarbazide derivatives based on triphenylamine-thiophene. • The structure, hydrogen bonding and spectronscopic properties of semicarbazide and thiosemicarbazide derivatives were investigated contrastingly. • The computational results discovered that thiosemicarbazide derivative transfers more electron from the donor groups to acceptor group than that of semicarbazide derivative. Two new thiosemicarbazide and semicarbazide derivative based on triphenylamine-thiophene, (E)-2-((5-(4-(diphenylamino)phenyl)thiophen-2-yl)methylene)hydrazine-1-carboxamide (L1) and (E)-2-((5-(4-(diphenylamino)phenyl)thiophen-2-yl)methylene)hydrazine-1-carbothioamide (L2), were synthesized and fully characterized by IR, 1H NMR, 13C NMR, MS and single crystal X-ray structural determination. Their structures are similar, contained the same donor groups of triphenylaminyl units (TPA), the core thienyl ring (thienyl-C), and the =N-NH-CX-NH 2 group (X = O, S) with different hetero atom. The absorption/emission maxima (in aspects of both wavelength and intensity) is altered by variation of the =N-NH-CX-NH 2 groups. To clarify the influence mechanism of the hetero atom in photophysical properties, the computational results of them under state specific PCM/TD1 PBE1PBE method were performed in DCM solvent and illustrated by hole-electron transition method, which the excitation and de-excitation of them are illustrated by hole-electron transition method. Furthermore, ADCH charge indicated that the electron is transferred from the donor groups of TPA and thienyl-C to acceptor group (=N-NH-CX-NH 2). The results illustrate that L2 transfers more electron from the donor groups to acceptor group (=N-NH-CS-NH 2) than that (=N-NH-CO-NH 2) of L1. Two derivatives of semicarbazide and thiosemicarbazide (L1, L2) were designed, synthesized, and their optical properties have been investigated on an experimental and theoretical basis. [Display omitted] [ABSTRACT FROM AUTHOR]

Using the density functional theory combined with the nonequilibrium Green's function, the transport properties of double-walled carbon nanotubes (DWCNTs) and carbon boronitride (CBN) heteronanotubes were investigated. As the hopping length increases, the conductance of DWCNTs shows a dramatic variation that is independent of the intertube space. The transport of the CBN heterojunctions also displays abnormal behavior when the hopping length is changed, which is very different from the behavior of DWCNTs. The currents of the forward in the CBN heterojunctions are about 3–15 times as large as those of the back under lower bias voltages. The negative differential resistance (NDR) effect occurs in the CBN heterojunctions, and the peak-to-valley ratio in the additional NDR regions is about 2–4 for the current–voltage relationship. The hopping length and BN parts have a great influence on the transport of the double-walled nanodevices. [ABSTRACT FROM AUTHOR]

An organic ligand (3-[4-(diphenylamino)styryl] pyridine, L) was synthesized. By complexation of L with ZnBr 2 and Zn(NCS) 2 respectively in methanol and dichloromethane, two complexes ZnBr 2 L 2 (dye1) and Zn(NCS) 2 L 2 (dye2) were prepared. The two dyes exhibit good one- and two-photon fluorescence performance with high fluorescence quantum yields and large two-photon absorption cross section values. The mechanism of one-photon absorption and one-photon excited fluorescence based on computational results was obtained by TDDFT/CAM-B3LYP method. The results of living cell imaging experiments exhibit their compatibility in cytoplasm of HepG2 cells and show their potential in fluorescence microscopy bioimaging Two new fluorescent complexes were prepared by complexation of a D-π-A structural organic ligand with ZnBr 2 and Zn(NCS) 2. The dyes exhibit good one- and two-photon excited fluorescence. They can localize in the cytoplasm, demonstrating their potential for fluorescence microscopy imaging application. [Display omitted] • Two new fluorescent complexes were obtained. • The complexes show one- and two-photon excited fluorescence with high two-photon absorption cross-section values. • Results of living cell imaging experiments show the value of the dyes in fluorescence microscopy bioimaging application. [ABSTRACT FROM AUTHOR]

By coordination of an electron donor-π-bridge-electron acceptor (D-π-A) optical functional organic ligand (L) with ZnBr 2 and HgBr 2 , two fluorescent complexes ZnBr 2 L (1) and HgBr 2 L (2) were obtained. The structures of them were solved by single crystal X-ray diffraction analysis. Study of linear and nonlinear optical properties has shown that the complexes exhibit excellent one- and two-photon excited fluorescence and large two-photon absorption cross-section values. Dye 1 shows the potential application in fluorescence microscopy bioimaging. Two fluorescent dyes ZnBr 2 L (1) and HgBr 2 L (2) were obtained. The dyes exhibit excellent one and two-photon excited fluorescence and large two-photon absorption cross-section values. Dye 1 shows the potential application in fluorescence microscopy bioimaging. Image 1 • Two fluorescent dyes ZnBr 2 L (1) and HgBr 2 L (2) were obtained. • The dyes show superior one- and two-photon excited fluorescence with large two-photon absorption cross-section values. • Results of living cell imaging experiments show the value of 1 in fluorescence microscopy bioimaging applications. [ABSTRACT FROM AUTHOR]