Explicit versus Implicit Solvation Effects on the First Hyperpolarizability of an Organic Biphotochrome

Abstract

The first hyperpolarizability of the four trans forms of a dithienylethene indolinooxazolidine biphotochrome in acetonitrile solution has been evaluated by using two solvation models, an explicit and an implicit one. The implicit solvation model is the integral equation formalism of the polarizable continuum model (IEF-PCM), whereas in the explicit one, the solvent molecules are represented by point charges, of which the positions have been generated by Monte Carlo simulations whereas the solute is treated quantum mechanically. At optical frequencies, first hyperpolarizabilities calculated with the implicit solvation model are usually larger than those obtained with the multiscale approach. However, both approaches predict similar contrasts, indicating that implicit solvation models such as IEF-PCM are well-suited to describe the variations in the NLO responses of molecular switches. In addition, the analysis of the contrasts of first hyperpolarizabilities shows that the biphotochrome can act as a three-state NLO switch.

Which charge definition for describing the crystal polarizing field and the χ(1) and χ(2) of organic crystals?

“…14 This approach has been employed to predict the relative stability of polymorphs of molecular crystals, 15 one of the most difficult challenges in crystal structures prediction. 20 The next step towards improving these QM/MM methods is the use of polarizable embedding. 17,18 For instance, in the same context as this Paper, i.e.…”

“…predicting the nonlinear optical (NLO) properties, this scheme has recently been used to describe the effects of concentration on the first hyperpolarizability of nibrobenzene in benzene 19 and the solvent effects on the first hyperpolarizability of molecular switches. 20 The next step towards improving these QM/MM methods is the use of polarizable embedding. This can be achieved by describing the surrounding at the DFT level of theory while the QM part is treated with correlated wave-function theory (WFT) method, leading to the so-called WFT-in-DFT scheme.…”

Second‐Order Nonlinear Optical Properties of a Dithienylethene–Indolinooxazolidine Hybrid: A Joint Experimental and Theoretical Investigation

“…For chloroform, e 0 = 4.711i nthe static field limit and e 1 = 2.091 at infinite frequency.T he relevance of this implicit solvation model to describe the NLO contrasts along the conversion pathways of this hybrid system was recently addressed by comparison to an explicit approach by combining quantum chemical calculations and Monte Carlo simulations. [29] Quantum chemical calculations reported herein were performed by using the Gaussian 09 package. [30] To provide insight into the relationship between second-harmonic generation (SHG) properties and molecular shapes, the unit sphere representation [31] was used to visualize the first hyperpolarizability tensor.T his method was based on the computation of an effective SHG dipole defined by Equation (6):…”

The first hyperpolarizability of nitrobenzene in benzene solutions: investigation of the effects of electron correlation within the sequential QM/MM approach

“…Therefore, the study of the surrounding effects on the NLO properties has attracted much interest, both theoretically and experimentally. Among these, both continuum and QM/MM methodologies were recently used to describe the solvent effects on the first hyperpolarizability (β, which describes, at the molecular level, the second-order NLO effects) contrast of molecular switches [25,26]. The NLO properties of molecules in solutions have been the object of intense investigations [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], where successive methodological developments have enabled to better understand solvation effects and to more closely account for experimental observations.…”