Synthesis, Photophysical, Electrochemical, and Non-linear Optical Properties of Triaryl Pyrazole-based B-N Coordinated Boron Compounds.

We report here a set of triaryl pyrazole based B-N coordinated boron compounds (11-17) synthesized by electrophilic aromatic borylation strategy. All the pyrazole boron compounds were thoroughly characterized using multinuclear NMR spectroscopy, LC-MS, and single crystal X-ray diffraction analysis (for 12-17). The photoluminescence measurements of 11-17 revealed that the emission peak maxima were tuned based on the substitution on N-phenyl. The photophysical and electrochemical properties were further supported by theoretical calculations. Z-scan based investigations at 515 nm pump wavelength showed that B-N coordination led to enhancement of nonlinear absorption (two-photon absorption (TPA)) in these compounds if an electron deficient moiety is attached. It has also been observed that an appropriate choice of moiety allows to optimally maneuver the molecular polarizability of the π-system and consequently, assists in controlling the third-order nonlinear optical response.

Synthesis of pyrazole anchored three-coordinated organoboranes and their application in the detection of picric acid.

Three-coordinated organoboron fluorophores bearing 3,5-diphenyl pyrazoles have been synthesized. The pyrazole anchored boron fluorophores show selective fluorescence quenching response to trinitrophenol (or) picric acid (PA) and have the ability to discriminate picric acid over other analytes. We investigated nonlinear optical (NLO) properties of these three-coordinated organoboron compounds (in solutions) in the presence and absence of PA. In absence of PA, the two-photon-absorption coefficient (ß) of organoboron fluorophores exhibits a variation from 2 × 10-12 cm W-1 to 4 × 10-12 cm W-1. The results also reveal that the NLO characteristics of organoboron fluorophores exhibit a discernible variation with PA addition which has correlations with quenching observed in fluorescence measurements.

Carbatriphyrin(3.1.1)-A Distinct Coordination Approach of BIII to Generate Organoborane and Weak C-H⋠⋠⋠B Interactions.

Carbatriphyrin(3.1.1) is the structural isomer of biphenylcorrole and achieved by switching the bonding mode of biphenyl unit from 3,3' to 2,3' which turns the corrole into a triphyrin analogue. The presence of a m-arene unit in the framework restricts the overall conjugation and thus leads to a nonaromatic macrocycle. The protonation experiments afford a trifluoroacetate ion complex. The coordination chemistry reveals that the bottom approach of boron(III) ion forms weak C-H⋅⋅⋅B interactions, however a top approach stabilizes the organoborane complex and the product distribution relies on the basicity of the proton scavengers. These results are unambiguously confirmed by single-crystal X-ray analyses.

Tetracoordinate Imidazole-Based Boron Complexes for the Selective Detection of Picric Acid.

N,N-Dimethylamine and N,N-diphenylamine-decorated highly fluorescent imidazole borates have been synthesized and investigated as new fluorophores for the selective detection of trinitrophenol/picric acid (PA). Structural studies of a probe 1 and PA (1·PA) complex revealed that the adduct formed by the deprotonation of PA by the -NMe2 group along with weak interactions is responsible for the selective detection of PA over other polynitrated organic compounds.

Design, synthesis, photophysical and electrochemical properties of 2-(4,5-diphenyl-1-p-aryl-1H-imidazol-2-yl)phenol-based boron complexes.

New hybrid organic-inorganic boron compounds using an imidazole core have been readily synthesized by a two-step procedure from commercially available simple starting materials. All boron compounds were fully characterized by multinuclear NMR spectroscopy, LC-MS, thermogravimetric analysis, cyclic voltammetry and single crystal X-ray diffraction analysis (for & ). The photoluminescence measurements of revealed distinct emission peak maxima located at 378, 379 and 387 nm, respectively. Electroluminescent devices fabricated using these boron compounds () suggest that the boron compounds are capable of transporting electrons. A maximum brightness of 6450 cd m(-2) at 12.5 V was realized when compound was used as an electron-transporting material.

Synthesis of a cyclometalated 1,3,5-triphenylpyrazole palladium dimer and its activity towards cross coupling reactions.

A phosphine free 1,3,5-triphenylpyrazole acetate-bridged palladacycle was prepared from simple commercially available starting materials. The activity of the palladacycle in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions was evaluated. The palladacycle precatalyst shows a wide substrate scope, both in Mizoroki-Heck as well as in Suzuki-Miyaura cross-coupling reactions using low catalyst loadings viz., 0.2 mol% and 0.1 mol% respectively.