Five napthyridine-based fluorine-boron (BF-napthyridine) conjugated compounds have been theoretically designed, and subsequently, their photophysical properties are investigated. The influence of electron-donating and electron-withdrawing groups attached with the NCO moiety of BF-napthyridine molecule has been interpreted. The optoelectronic properties, including absorption spectra and emission spectra of the BF-napthyridine derivatives are studied using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) based methods. Different characteristics, such as HOMO-LUMO gap, molecular orbital density, ionization potential, electron affinity, and reorganization energy for hole and electron, are calculated. All these molecules show excellent π-electron delocalization. TD-DFT results illustrate that the amine-substituted BF-napthyridine derivative has the highest absorption and emission maxima; it also shows a maximum Stoke shift. These results are well-correlated with the structural parameters and calculated HOMO-LUMO gap. Moreover, it is found that introduction of an electron-donating group into the BF-napthyridine complex improves the hole transport properties and provides useful clues in designing new materials for organic light emitting diodes (OLED). As a whole, this work demonstrates that electron-donating and electron-withdrawing groups in BF derivatives can extend their effectiveness toward designing of OLED materials, vitro cellular studies, ex vivo assays, and in vivo imaging agents.

Six indole based thiazole substituted donor-π-acceptor molecules are designed and their nonlinear optical properties (NLO) are evaluated theoretically. Different electron withdrawing groups and π-linkers are used to understand their role in tuning the NLO properties. The NLO properties of the molecules are analyzed in gas phase and in different solvent medium through the dipole moment, static polarizability, first and second hyperpolarizabilities. Efficiency of the molecules are studied through HOMO-LUMO gap, frontier molecular orbitals, light harvesting efficiency, ionization potential, electron affinity and reorganization energy for hole and electron. All the dyes show maximum absorption wavelength in the visible region. The computed absorption spectra are well correlated with the HOMO-LUMO gaps of the molecules. The HOMO-LUMO gaps of all the dyes are found to be small, which lead to large NLO response. Results indicate that hyperpolarizability increases with increasing strength of the electron withdrawing group. In addition to the study of nonlinear optical property, we also calculate relevant parameters related to photovoltaic cells for two designed dyes which emerge suitable for this purpose. Photovoltaic parameters such as electron injection efficiency, exciton binding energy, and open circuit photovoltage are evaluated for dye sensitized solar cells (DSSC) applications. This study shows that alkyne π-linkers are better than the alkene π-linkers for desired applications. Overall, this study highlights the optical and photovoltaic nature of the dyes and reveals the influence of different πlinkers and electron acceptors in designing new materials for NLO and DSSC applications.[a] T.

Cystine-based gemini surfactants with dodecyl, tetradecyl, hexadecyl, and octadecyl hydrocarbon chains were synthesized, and their interactions with unsaturated (soy phosphatidylcholine, SPC)/saturated (hydrogenated SPC, HSPC) soy phosphatidylcholines in the forms of a monolayer and a model liposome were estimated for different combinations of the components in the mixed systems. Studies of Langmuir monolayers at the air-aqueous buffer interface revealed condensation of the monomolecular films with the addition of surfactants. The effect of surfactants decreased according to the following order: octadecyl > hexadecyl > tetradecyl > dodecyl homologs. The nonideal mixing between the components was estimated using the deviation of the experimental molecular area from the ideal area per molecule. The excess molecular area increased with the increase in the surfactant chain length and phospholipid saturation. The 50 mol % mixture of cystine derivatives and phospholipids formed thermodynamically stable monolayers. The surfactants increased the rigidity of SPC monolayers and decreased that of HSPC monolayers, as observed by the studies of surface dialational rheology. The film structure at the air-water interface could differentiate the SPC- and HSPC-comprising systems through the formation of organized regions, especially at a higher surface pressure. The constriction of surfactant/phospholipid hybrid vesicles was observed with an increase in the length of surfactant hydrocarbon chains. The negative zeta potential of vesicles took the highest values and did not change with time for 20 and 50 mol % surfactant. The spherical shape of the vesicles was confirmed by transmission electron microscopy. Differential scanning calorimetry revealed an increase in fluidity of HSPC bilayers and rigidity of SPS bilayers under the influence of surfactants. These effects were confirmed by fluorescence spectroscopy. All of the vesicle formulations were found to be nontoxic from the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay, suggesting their potential as a novel membranous system for the delivery of drugs, genetic materials, vaccines, and other therapeutic agents.

BODIPY-based zwitterionic molecules with pyridinium and imidazolium electron acceptors and thienothiophene π-linkers reveal significant first hyperpolarizability.

The influence of donor−acceptor (D−A) groups on the nonlinear optical (NLO) property of B 12 N 12 functionalized nanocluster has been investigated by density functional theory. We study the effect of bonding of three electron acceptor ligands (CN, COOH, and NO 2 ) and three donor ligands (NH 2 , N(CH 3 ) 2 , and PhNH 2 ) positioned at opposite ends of B 12 N 12 nanocluster in the gas phase. The result reveals that the complexation of D−A groups on the B 12 N 12 nanocluster is energetically favorable and significantly narrowed the HOMO−LUMO gaps. The functionalization of D−A groups lead to an extremely large first hyperpolarizability value. Our survey reports the strongest NLO responses found in PhNH 2 −B 12 N 12 −PhCN cluster (1882.47 × 10 −30 esu), whereas centrosymmetric B 12 N 12 cluster yields a zero hyperpolarizability value. Designed systems are analyzed through the HOMO−LUMO gap, frontier molecular orbital, hyperpolarizability, Δr index, transition dipole moment density, density of states (DOS), and molecular electrostatic potential. The obtained results are well correlated with the computed absorption spectra of the molecule. The results demonstrate that phenyl ring incorporated D−A groups amplify the NLO response to a larger extent. The significant first hyperpolarizability arises due to charge transfer from the donor to the acceptor moiety. As a whole, this theoretical work provides a direction to researchers that the right choice of substitution can considerably impact the nonlinear optical property of BN nanoclusters.