We demonstrated for the first time that, at temperatures below the melting point of a given polar solvent, the emission of some four-coordinate monoboron complexes containing monoanionic bidentate (NO) ligands shifted to lower wavelengths, but no such shift was observed for studies conducted in nonpolar solvents. This means that the emission from a polar solvent appears at shorter wavelengths if compared with that from a nonpolar solvent when the measurement was performed at low temperatures, a phenomenon totally different from that observed for conventional solvatochromic fluorophores. The finding was rationalized by considering the temperature-dependent conformational relaxation of the tetrahedron monoboron complexes from their local excited (LE) state to their relaxed excited (RE) state. Further studies revealed that variating the structure of the chelating ligands could result in remarkable changes in the fluorescent colors of the monoboron complexes. However, changing the structure of other two monodentate ligands showed little effect upon the fluorescence property of the compounds. Therefore, it is anticipated that the monoboron complexes may be taken as a platform to construct a variety of functional molecular systems via alternating the structure of the chelating ligand and that of the monodentate ligand. As an example, naphthalene was introduced as a monodentate ligand, and independent emissions from naphthalene unit and the other part of the monoboron complex as well as intramolecular energy transfer between them were observed. It is believed that the present work provides a new insight into the monoboron complexes, laying the foundation for them to be explored for developing novel molecular systems.

Nitrogen-containing heterocyclic complexes are important parts of many biological molecules including DNA, RNA, proteins and drug molecules, which often have weak intermolecular interactions. Theoretical understanding based on the density functional theory (DFT) of such subtle interactions is of importance but challenging since it is strongly dependent on the choice of the DFT exchange–correlational (XC) functionals. In this study, the performances of 20 DFT XC functionals at the different DFT levels for calculating the intermolecular interactions of nitrogen-containing heterocycles have been evaluated using 23 representative complexes. The benchmark intermolecular interactions are derived from the calculations using the “golden standard” CCSD(T)/CBS method. Our results demonstrate that the XC functionals with the consideration of dispersion forces have the better performance on evaluation of intermolecular interaction. Overall, the functional with the best performance is ωB97M-V for calculating non-bonding interactions of nitrogen-containing heterocyclic complexes, while other XC functionals may outperform it for individual stacking configurations. To reduce the computation cost, the relatively small basis set can be used when the Boys-Bernardi counterpoise corrections are applied.

The solvated supermolecular approach, i.e., block-localized wave function coupled with polarizable continuum model (BLW/PCM), was proposed to calculate molecular ionization potential (IP), electron affinity (EA) in the solid phase, and related electronic polarization. Via the calculations of a solvated supermolecule (5M), including four closest molecules, BLW/PCM overcomes the limitation in the calculation for the monomer PCM, that is, nearly same electronic polarization for cation (P+) and anion (P−). The solvated supermolecular approach successfully described asymmetric behaviors of P+ and P− for oligoacene crystals. In addition, we also compared two charge-localized methods, i.e., BLW and constrained density functional theory (CDFT), to calculate the molecular IP and EA in supermolecules with/without PCM. Our results demonstrate that both the BLW and CDFT correctly estimate the EA and IP values in the gas phase cluster, whereas CDFT/PCM fails to evaluate the P− value of the bulk system.

•Apply computational molecular modeling approaches to screen a new tetrazole-based energetic material—1-amino-5-nitrotetrazole (ANTz).•Predict its energy, density and pyrolysis pathway.Ideal energetic materials should first possess high energy and high crystal density for their practical applications. In this study, a new energetic material—1-amino-5-nitrotetrazole (ANTz) has been molecularly designed. ANTz has been demonstrated to possess highest gas-phase heat of formation (HOF) based on our theoretical calculations of 14 derivatives of tetrazole. Its high density value equally demonstrated its excellent performance. However, computational impact sensitivity (h50) has a great derivative with experimental BAM test impact sensitivity value for recently synthesized 2-amino-5-nitrotetrazole, which is ANTz’s isomer. That makes us doubt the QSPR model of predicting impact sensitivity for tetrazole derivatives. Although we cannot precisely predict its impact sensitivity for the lack of suitable theoretical methods and incomplete database, ANTz is expected to be a good candidate as energetic material from the perspective of energy and density. The pyrolysis pathways of ANTz were also systematically analyzed, which demonstrated that ANTz is prone to decompose by direct ring rupture from a reaction kinetic perspective. And its preferable final products are HNO2, N2 and CN3H.

A fluorescent sensing ensemble for citrate has been developed, which is composed of a meta-phenylboronic acid substituted dipyrido[3,2-a:2′,3′-c]-7-aza-phenazine copper(I) complex ([Cu(L1)2]) and aspartic acid modified perylene diimide (PASP). The complex [Cu(L1)2] can bind to PASP with a molar ratio of 2:1 ([Cu(L1)2]/PASP), and the fluorescence of PASP is efficiently quenched due to photoinduced electron transfer (PET) from PASP to [Cu(L1)2] (ΦET = 0.53). Highly selective “turn-on” type fluorescence changes are observed upon addition of citrate, with an emission enhancement (F/F0) of about 1500-fold when the concentration of citrate is 40 mM. The fluorescence enhancement shows an excellent linear relationship (R2 = 0.9972) with the concentration of citrate in the range of 25 μM to 1 mM, indicating that the PASP/[Cu(L1)2] ensemble is sensitive to citrate. In contrast, there is little change in the emission intensity of the [Cu(L1)2]/PASP ensemble upon addition of the other α-hydroxycarboxylates, dicarboxylates or monosaccharides (≤1 mM). The phenylboronic acid substituent and copper(I) ions are essential for the sensing selectivity.

polarization energy of the localized charge in organic solids consists of electronic polarization energy, permanent electrostatic interactions, and inter/intra molecular relaxation energies. The effective electronic polarization energies for an electron/hole carrier were successfully estimated by AMOEBA polarizable force field in naphthalene molecular crystals. Both electronic polarization energy and permanent electrostatic interaction were in agreement with the preview experimental values. In addition, the influence of the multipoles from different distributed mutipole analysis (DMA) fitting options on the electrostatic interactions are discussed in this paper. We found that the multipoles obtained from Gauss-Hermite quadrature without diffuse function or grid-based quadrature with 0.325 Å H atomic radius will give reasonable electronic polarization energies and permanent interactions for electron and hole carriers.

Quantitative agreement has been found between observed and calculated charge mobilities through organic conductors, despite the use of many assumptions in the calculations, including: the relative strength of the intermolecular electronic coupling to the reorganization energy driving charge localization, the treatment of site variability in the material, the involvement of tunneling processes during charge hopping between sites, the use of weak-coupling-based perturbation theory to determine hopping rates, the residence times for charges on sites, the effect of the large field strengths used in experimental studies, the general appropriateness of simple one-dimensional diffusion modeling approaches, and the involvement of molecular excited states of the ions. We investigate the impact of these assumptions, concluding that all may be very significant. In some cases, methodological options are considered, and optimum procedures are determined, showing that (i) the use of Koopmans' theorem to estimate intermolecular couplings in solids is problematic and (ii) the correct expression for the residence lifetime of a charge on a crystal site. These conclusions are drawn from simulations of anisotropic charge mobilities through the β phase of mer-tris(8-hydroxyquinolinato)aluminum(III) (Alq3) crystal, a material commonly used in OLED applications. Calculations are compared that determine mobilities at finite applied field from drift velocities through either semianalytical solutions of the master equation or else kinetic Monte Carlo simulations, as well as those that determine mobilities from multidimensional diffusion coefficients at zero field by Monte Carlo and those that analytically solve simplified one-dimensional diffusion models. For crystalline Alq3 itself, the calculations predict electron mobilities that are 4–6 orders of magnitude larger than those predicted by similar methods for amorphous Alq3, in agreement with experimental findings. This work vindicates recent theories describing the poor mobilities of the amorphous material, forming a complete basic picture for Alq3 conductivity.

The steady state master equation coupled Marcus–Hush electron transfer theory is developed to calculate the two-dimensional electron and hole mobilities in pentacene ab-plane. In this paper, we numerically investigated the influences of the random distributed traps and charge-carrier densities on the 2D mobilities. The study showed that shallow traps (<7.5kT) give few effects on the mobilities for various carrier densities, while deep traps (>10kT) remarkably decrease mobilities, in particularly, when the carriers density cannot quenched them. However, when the traps are fully quenched due to large carrier densities, the mobility will be nearly back to their intrinsic mobility values.

The master equation coupled with the Marcus–Hush electron transfer theory is applied to solve the charge-carrier mobility in pentacene ab-plane. The two-dimension mobilities of hole and electron-carriers are calculated by numerical method. The calculated intrinsic mobilities for hole and electron-carriers are same order of magnitude. The field induced anisotropic hole-carrier mobilities basically agree with Lee et al. experimental results [J.Y. Lee, S. Roth, Y.W. Park, Appl. Phys. Lett. 88 (2006) 252106]. The direction of the highest hole-carrier mobility is clearly assigned. The influences of electric field and carrier density on the mobility are also investigated.

The solvated supermolecular approach, i.e., block-localized wave function coupled with polarizable continuum model (BLW/PCM), was proposed to calculate molecular ionization potential (IP), electron affinity (EA) in the solid phase, and related electronic polarization. Via the calculations of a solvated supermolecule (5M), including four closest molecules, BLW/PCM overcomes the limitation in the calculation for the monomer PCM, that is, nearly same electronic polarization for cation (P+) and anion (P−). The solvated supermolecular approach successfully described asymmetric behaviors of P+ and P− for oligoacene crystals. In addition, we also compared two charge-localized methods, i.e., BLW and constrained density functional theory (CDFT), to calculate the molecular IP and EA in supermolecules with/without PCM. Our results demonstrate that both the BLW and CDFT correctly estimate the EA and IP values in the gas phase cluster, whereas CDFT/PCM fails to evaluate the P− value of the bulk system.