scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Synthesis, characterization and photophysical studies of a novel polycyclic diborane

TL;DR: In this paper, the X-ray structure analysis reveals that 2 has a twisted structure (dihedral angle ≈ 21.75°) with a rather short B-B bond (1.667(9) A).
Abstract: Treatment of tetrakis(dimethylamino)diboron (B2(NMe2)4) with 1,4-bis(2-(triisopropylsilyl)ethynyl)naphthalene-2,3-diamine (1) generated a large NBBN polycyclic compound 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2). The X-ray structure analysis reveals that 2 has a twisted structure (dihedral angle ≈ 21.75°) with a rather short B–B bond (1.667(9) A). Theoretical calculations on 1,1-B2 isomer 2 and its counterpart 1,2-B2 isomer 3 have been conducted to understand their frontier orbital energy levels. Compound 2 shows strong emission with a high quantum yield of 0.52, despite the presence of many unbeneficial non-radiative behaviors such as the vibration of the TIPS groups and the rotation of the B–B single bond.
Citations
More filters
Journal ArticleDOI
TL;DR: Compounds 4, 6 and 7 are characterised by elemental analyses, 1H, 11B and 13C NMR spectroscopy, as well as by single X-ray diffraction studies, and the electronic structures of 4, 7 are subject to DFT calculations.
Abstract: Colorless crystalline 2,6-dibromo-4,8-dimethyl-1,3,5,7-tetraphenylbenzobis(diazaborole) 4 resulted from the cyclocondensation of 3,6-dimethyl-1,2,4,5-tetraphenylaminobenzene 3d with two equivalents of boron tribromide in the presence of calcium hydride. Synthesis of the dark-red crystalline 2-bromo-N,N'-bis(diisopropylphenyl)acenaphtho-1,3,2-diazaborole 7 was effected by the cyclocondensation of 1,2-bis(N-2',6'-diisopropylphenylimino)acenaphthene (5) and boron tribromide with subsequent sodium amalgam reduction of the initially formed burgundy red diazaborolium salt 6. Compounds 4, 6 and 7 are characterised by elemental analyses, 1H, 11B and 13C NMR spectroscopy, as well as by single X-ray diffraction studies. The electronic structures of 4, 6 and 7 are subject to DFT calculations.

10 citations

Journal ArticleDOI
TL;DR: This work is presenting the syntheses of a series of T-shaped NBN-embedded dibenzophenalene derivatives through the formation of a key brominated intermediate in a stoichiometrically controlled reaction.
Abstract: Small organic molecules with finely tunable physical properties are extremely desired for the fabrication of low-cost and high-performance organic electronic devices In this work, we are presenting the syntheses of a series of T-shaped NBN-embedded dibenzophenalene derivatives through the formation of a key brominated intermediate in a stoichiometrically controlled reaction The geometric and electronic structures of these T-shaped molecules can be simply tailored via attaching substituents along the direction perpendicular to the molecular main backbones, resulting in substantial physical properties, such as high thermal stability with a decomposition temperature of more than 350 o C, intensive blue luminescence with quantum yield up to 062 Organic light emitting diode device fabricated from such type of molecule as the emitting layer releases pure blue light with CIE (016, 012)

8 citations

Journal ArticleDOI
01 Apr 2021
TL;DR: In this paper, two kinds of ladder-type conjugated polymers were synthesized by the formation of single-stranded conjugation via Stille cross-couplings, followed by nitrogen-directed electrophilic borylations at electron-rich aromatic rings.
Abstract: Two kinds of ladder-type conjugated polymers were concisely synthesized by the formation of single-stranded conjugated polymers via Stille cross-couplings, followed by nitrogen-directed electrophilic borylations at electron-rich aromatic rings. The resulting BN-annulated polymers show good film-forming behaviors and high air and thermal stability. Their structurally shape-persistent rigid backbones render them with π-extended conjugation, allowing for efficient light harvesting in the low-energy regions, and emitting strong fluorescence with narrow emission widths.

2 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Abstract: Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155 (1992)], we believe that further improvements are unlikely unless exact‐exchange information is considered. Arguments to support this view are presented, and a semiempirical exchange‐correlation functional containing local‐spin‐density, gradient, and exact‐exchange terms is tested on 56 atomization energies, 42 ionization potentials, 8 proton affinities, and 10 total atomic energies of first‐ and second‐row systems. This functional performs significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.

87,732 citations

Journal ArticleDOI
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Abstract: A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.

84,646 citations

Journal ArticleDOI
TL;DR: This paper could serve as a general literature citation when one or more of the open-source SH ELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.
Abstract: An account is given of the development of the SHELX system of computer programs from SHELX-76 to the present day. In addition to identifying useful innovations that have come into general use through their implementation in SHELX, a critical analysis is presented of the less-successful features, missed opportunities and desirable improvements for future releases of the software. An attempt is made to understand how a program originally designed for photographic intensity data, punched cards and computers over 10000 times slower than an average modern personal computer has managed to survive for so long. SHELXL is the most widely used program for small-molecule refinement and SHELXS and SHELXD are often employed for structure solution despite the availability of objectively superior programs. SHELXL also finds a niche for the refinement of macromolecules against high-resolution or twinned data; SHELXPRO acts as an interface for macromolecular applications. SHELXC, SHELXD and SHELXE are proving useful for the experimental phasing of macromolecules, especially because they are fast and robust and so are often employed in pipelines for high-throughput phasing. This paper could serve as a general literature citation when one or more of the open-source SHELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.

81,116 citations


Additional excerpts

  • ...MALDI-TOF spectrum of 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2)....

    [...]

  • ...13C NMR spectrum of 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2) in CDCl3....

    [...]

  • ...HRMS-TOF spectrum of 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2)....

    [...]

  • ...Compound 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2) CCDC 1866611 T (K) 100 Formula C64H96B2N4Si4 Formula weight 1055....

    [...]

  • ...1H NMR spectrum of 1,1-B2{2,3-(NH)2-1,4-(iPr3SiC2)2C10H4} (2) in CDCl3....

    [...]

Journal ArticleDOI
TL;DR: Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable and highlighted the accessible barriers for C- H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.
Abstract: A number of studies were conducted to demonstrate C-H activation for the construction of C-B bonds. Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable. The reaction at a primary C-H bond of methane or a higher alkene B 2(OR)4 formed an alkylboronate ester R' -B(OR)2 and the accompanying borane H-B(OR2. The ester and the borane were formed on the basis of calculated bond energies for methylboronates and dioaborolanes. The rates of key steps along the reaction pathway for the conversion of a C-H bond in an alkane or arene to the C-B bond in an alkyl or arylboronate ester were favorable. These studies also highlighted the accessible barriers for C-H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.

2,108 citations

Related Papers (5)