Enhancement of molecular polarizabilities by the push-pull mechanism; a DFT study of substituted benzene, furan, thiophene and related molecules

Abstract

Abstract:We report Density Functional Theory (DFT) studies of the dipole polarizabilities of benzene, furan and thiophene together with a number of substituted and related systems. All geometries were optimized (and characterized) at the B3LYP/6-311g(2d,1p) level of theory and polarizabilities then calculated with B3LYP/6-311++G(2d,1p). For the R-ring systems we find group polarizabilities in the order R = NO 2 ∼ OCH 3 ∼ CN ∼ CHO > NH 2 > OH > H = 0. For systems R-ring-R, <α> differs little from the additivity model, with small positive and negative increments. For systems D-ring-A (where D and A are deactivating and activating groups) we find a positive enhancement to <α> over and above the value expected on the basis of pure additivity for all pairs A and D studied. This enhancement can be increased greatly by extending the length of the conjugated chain to D-ring-CH=CH-ring-A and D-ring-N=N-ring-A systems. Empirical models of polarizability such as AM1 agree badly with the DFT calculations in an absolute sense but give excellent statistical correlation coefficients. Calculated <α>'s also agree well in a statistical sense with the molecular volumes calculated from molecular mechanics force fields Analysis of the results in terms of the π electrons alone is not satisfactory.

Photoactive Zr-aromatic hybrid thin films made by molecular layer deposition

“…The long 26-NDC linker decreases the wettability of the surface (higher contact angle). Furthermore, the presence of -NH 2 , and -OH groups can increase the polarizability and thus its wettability, 28,29 which is consistent with the measured contact angles for Zr-2A-BDC and Zr-25D-BDC. Additionally, we show an evolution of the contact angle versus time.…”

Regioselective Plasmonic Coupling in Metamolecular Analogs of Benzene Derivatives

“…18 nm/NS. The synergistic effect found here is analogous to the positive enhancement in the molecular polarizability of benzene by certain activating functional groups …”

“…The synergistic effect found here is analogous to the positive enhancement in the molecular polarizability of benzene by certain activating functional groups. 37 In assemblies with multiple NSs, the respective placement of NSs on the NP must dictate the nature of plasmonic coupling and the resulting spectral characteristics of the assembly. In contrast to the uniform distribution of NSs, shown in Figure 5, we found some instances of NSs asymmetrically distributed around the NP sides (Figure 6A,B).…”

Implementation and Optimization of DFT-D/COSab with Respect to Basis Set and Functional: Application to Polar Processes of Furfural Derivatives in Solution

“…A particular case of longstanding interest is the barrier to rotation in push−pull furfural systems, especially due to their importance as components in many biological redox centers and synthetic molecular devices. − Moreover, these systems have associated experimental as well as computational challenges . For example, the very small energy difference between the cis and trans isomers, the possibility for secondary interactions in some of the analogues as well as the strong solvent dependencies across a small range of dielectric (particularly for the parent furan-2-carbaldehyde system), creates particular challenges for both experimental as well as computational predictions.…”