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A new family of dimeric B/N Lewis pairs with sterically tunable substitutions has been accomplished using the Two-in-One design strategy. Their structures are characteristic of doubly B/N-containing cores, and the electronic interactions between B and N centers can be modulated by the steric effects of ortho-substitutions from methyl groups. Interestingly, unique white-light emissions were achieved for 2M′2BNMand 1M2BNM, ascribed to the integration of two triarylborane species (Bsp2- and Bsp3-hybridization) into one single molecule.

Triarylborane (Ar3B) and triarylamine (Ar3N) have been widely employed to construct electronically different donor–acceptor (D–A) systems. Herein, we describe a series of A–D–A-type luminescent organoboranes L-B2Nn(n= 1, 3, 5) that show an increased number of Ar3N units as electron donors and two terminal Ar3B as acceptors. When the Ar3N moieties were extended from one to five units, their electron-donating strength was gradually enhanced and the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gaps could also be tuned, which was further reflected in the red-shifted emissions from blue (λem= 458 nm) to orange (λem= 595 nm) with a decrease in Egap(elect)from 3.19 to 2.61 eV. L-B2N5showed a huge Stokes shift (∼14 057 cm–1) and a considerably bright emission with an enhanced solid-state quantum efficiency (ΦS= 98%) compared with the other members. L-B2N3and L-B2N5exhibited aggregation-induced emissions (AIEs), and an apparent solvatochromic shift was also observed in the emission spectra as the solvent was changed from hexane to tetrahydrofuran (THF) (430 → 595 nm). In addition, the donor–acceptor charge-transfer character in these organoboranes caused a thermally responsive emission over a broad range.

Chiral luminescent triptycenes (HC-BNand HC-BB) functionalized with electron-donating carbazole and electron-accepting triarylborane were synthesized by classical Buchwald-coupling and Suzuki-coupling reactions. The compound bearing both carbazole and triarylborane, HC-BN, exhibits significant thermochromic shift of the emission because of the intramolecular charge transfer (ICT) character. Their chiral optical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL), are further studied because of the inherent chirality of triptycene derivatives. This work may contribute to the development of new chiral luminescent materials based on the rigid, homoconjugated, and structurally unusual three-dimensional triptycene scaffolds.

A series of dicyanomethylene-functionalized triarylboranes is reported in this work, with low-lying LUMO energy levels at ca. −3.66 eV for FMesB-ACN. The single-crystal structures of the mono- and dianion of Mes*B-ACNwere obtained via chemical reduction, which revealed a conversion from a quinoidal to an aromatic structure. The strong Lewis acidity of these compounds is reflected in a fluoride-anion binding experiment. This work introduces a facile strategy for modulating the electron deficiency of boron-containing compounds.

BN-doped polycyclic aromatic hydrocarbons (PAHs) have attracted numerous attentions because of their fascinating optical and electronic properties. In this work, a series of electron-donor (amine)- and -acceptor (borane)-functionalized BN-doped polycyclic aromatic hydrocarbons were prepared to study the substituents’ effect on the photophysical properties. As a result, the compound with both donor and acceptor, BN, exhibits both local emission (LE) and charge-transfer emission (CT) in polar solvents. Especially, the CT emission with a longer wavelength revealed a lifetime as long as millisecond time scale at room temperature, indicating typical phosphorescence characteristics. Low-temperature photoluminescent (PL) spectroscopy and a theoretical study were conducted to help to interpret this phenomenon, and it turned out to be the lowering of the S1energy level of BNwhich makes the intersystem crossing favorable. Furthermore, fluoride anion titration experiments exhibit the application potential of the dual-emission phenomenon of BNfor ratiometric sensory materials.

We present a family of stilbene derivatives (1–4) ortho-functionalized with an electron donor and acceptor. Their emission was tuned by donor substitutions, dictating charge transfer dependent on the N···B spatial separation. The steric reduction of substituents on N leads to stronger emission responses upon trans-to-cis photoisomerization. Upon further approach, a bistable isomer was photochemically achieved (4: R1= Me, R2= H) with quenched emission, which is ascribed to the pronounced B···N constraint via B ← NH coordination in cis-4.

π-Conjugated azobenzene derivatives were reported to couple azo moieties with aryl fluorophore. Using the photochemistry of the C2-bridged azobenzene, we have accomplished two diazocine-based photoswitching molecules (cAz1and cAz2). In addition to remarkable photochromic properties, they show a turn-on fluorescence, and the emission was highly enhanced with quantum efficiency increasing up to 0.22 for cAz1. The emission remains persistent and can only be switched off via thermal deactivation. They display greater optical responses, compared with the linear analogues (Az1–Az4). This work may provide a new scaffold toward advanced light-emitting materials using photoswitchable systems.

Facile synthesis of BN-functionalized azaborines (4a–4c) was accomplished via Suzuki coupling reactions followed by the electrophilic C–H borylation of benzotrithiophene (BTT). The core structure of BTTenables multiple modifications at the three thiophene rings. Molecular structures of 4a–4cwere confirmed by NMR, high-resolution mass spectrometry, and X-ray crystallographic analysis. Their electronic properties were also examined through photophysical and electrochemical measurements as well as density functional theory computations. The red-shifted absorption and emission of these molecules were demonstrated upon fluoride titration in response to anion binding, leading to a remarkable decrease of the oxidation potential in the electrochemical differential pulse voltammetry scans. This work may provide a new pathway to robust redox-active materials for catalytic applications.

A series of robust organoboranes with electronically tunable functionality of B/N Lewis pairs has been achieved. These compounds feature a B/N-containing core in which the interactions between the B and N atoms are modulated as a result of the structural flexibility of the nonconjugated backbone. Examination of the substituent effects of the Lewis base moiety reveals that bulky or aryl substituents favor the dynamic switching of the B–N bond in response to external stimuli, such as heat or mechanical pressure, leading to emission color modulation. This work provides a new, straightforward proof of concept toward new switchable materials design based on tunable electronic interactions.

This paper presents new chiral luminescent molecules (N7-BMes2and N7-TTM) using configurationally stable aza[7]helicene (1) as a universal heteroatom-doped chiral scaffold. The respective reactions of electron-donating 1with a triarylborane acceptor via palladium-catalyzed Buchwald–Hartwig C–N coupling and with the open-shell doublet-state TTM radical via nucleophilic aromatic substitution (SN2Ar) resulted not only in tunable emissions from blue to the NIR domain but also in significantly enhanced emission quantum efficiency up to Φ = 50%.

Highly emissive π-conjugated macrocycles with tunable circularly polarized luminescence (CPL) have sparked theoretical and synthetic interests in recent years. Herein, we report a synthetic approach to obtain new chiral organoborane macrocycles (CMC1, CMC2, and CMC3) that are built on the structurally chiral [5]helicenes and highly luminescent triarylborane/amine moieties embedded into the cyclic systems. These rarely accessible B/N-doped main-group chiral macrocycles show a unique topology dependence of the optoelectronic and chiroptical properties. CMC1and CMC2show a higher luminescence dissymmetry factor (glum) together with an enhanced CPL brightness (BCPL) as compared with CMC3. Electronic effects were also tuned and resulted in bathochromic shifts of their emission and CPL responses from blue for CMC1to the near-infrared (NIR) region for CMC3. Furthermore, chemical oxidations of the N donor sites in CMC1gave rise to a highly stable radical cation (CMC1·+SbF6–) and diradical dication species (CMC12·2+2SbF6–) that serve as a rare example of a positively charged open-shell chiral macrocycle.

Stable organic radicals with unique luminescence show great importance in photoelectromagnetic materials. We herein report two unusual radical-based systems (P5N-TTMand P5B-TTM) using the concerted effects of planar chiral pillar[5]arenes and tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. The steric effect and electronic doublet-spin character of these radicals allowed the optical resolution and the first red emissions (∼650 nm) for pillar[5]arene derivatives. Notably, cross-coupling with macrocyclic pillar[5]arene, in turn, considerably enhanced the configurational stability of TTMradicals.

Dimesitylboryl-acceptor (A) and diarylamine-donor (D) substituents are introduced at α positions of BN-doped tetrathienonaphthalene in the same and opposite directions of the B–N bond, namely, B-BN-Nand N-BN-B, in order to demonstrate how the substitution patterns influence the photophysical properties. The photophysical and electrochemical properties of these D-π-A molecules have been investigated in detail, aided by UV–vis absorption and fluorescence spectroscopy as well as cyclic voltammetry. We find that both B-BN-Nand N-BN-Bshow the typical intramolecular charge transfer emission. N-BN-Bexhibits strong fluorescence with a narrower band gap and stronger Lewis acidity than that of B-BN-N. DFT calculations help give a reasonable explanation that subtle differences in the electronic structure of the host skeleton could also influence the substituents and feed back this effect to the entire molecule.

We herein describe the synthesis of two axially chiral systems (HBNand BBN) by the incorporation of B centers into binaphthyl derivatives (HPyand BPy). Heteroatom-doped chiral polycyclic aromatic hydrocarbons were thus formed by fusion of the azaboroles to binaphthyls with the formation of B–N dative bonds. The resulting B–N Lewis pairs that serve as attractive fluorophores enabled modulation of the chiroptical properties both in solution and in the solid state.

A novel T4(1) water chain in a new CuII coordination polymer, {[Cu(C4H6N2)2(C4H2O4)] (H2O)3}n (1, where C4H6N2 = 2-methylimidazole, C4H2O4 = maleate), has been synthesized and structurally characterized by single-crystal X-ray diffraction. Thermogravimetry, infrared spectroscopy, elemental analysis, and magnetic analysis have also been used to characterize 1. Complex 1 crystallizes in the trigonal space group P3221, and the 1-D chains composed of cyclic water tetramers play an important role in stabilizing the overall polymeric structure. Furthermore, this 1-D water chain presents an unusual association mode of water molecules.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

A series of 3,6-di-tert-butyl carbazole-functionalized 9-borafluorene derivatives have been prepared with outstandingly strong photoluminescence with quantum yields up to ca. 100 and 94% for Mes*BF-pCzin solution and film, respectively. 1,3,5-Tris(trifluoromethyl)benzene (FMes)-substituted compounds exhibit enhanced Lewis acidity with coordination to weak nucleophiles like tetrahydrofuran, resulting in a long afterglow at low temperature. The large two-photon absorption cross-section of ca. 1103 GM for Mes*BF-pCzat 800 nm in CH2Cl2indicated its potential application in bioimaging.

We first describe two examples of highly luminescent organoboranes (NP5BN1and NP5BN2) with dual chirality that were achieved by molecular functionalization of planar chiral pillar[5]arenes with naphthyls. Sufficiently strong steric effects are imposed by triarylamine (Ar3N) and triarylborane (Ar3B) moieties and further enhanced by the proximity of the chiral building blocks, leading to the isolation of multiple enantiomers via chiral high-performance liquid chromatography. The intramolecular charge transfer from N-donor to B-acceptor across both chiral subunits enabled the circularly polarized luminescence and thermally robust colorimetric responses in their emissions. Furthermore, their remarkable host–guest chemistry was allowed at no expense in the pursuit of advanced chiroptical properties using pillar[5]arene-based supramolecular scaffolds.

Two diazaborepins (BNN1and BNN2) have been accomplished via a highly efficient pathway in the step-economic transformation. Oxidative dimerization of carbazole derivatives followed by borylation reaction gave heterocyclic diazaborepin as the key building block. Replacement of carbon moiety in traditional borepins with N–N functionality led to a significant red shift of their emissions up to 585 nm with strong red color as solids. This work offered an approach to diazaborepin-based materials for applications in light-emitting field.