Remote Functionalized Nonlinear Optical Chromophore:  Optimal Assembly in Crystals for Second Harmonic Generation

Abstract

Structural investigations of salts of 4-nitroaniline (pNA) and N-(2-aminoethyl)-4-nitroaniline (AENA) with S-10-camphorsulfonic acid reveal that the introduction of the remote amino functionality in AENA facilitates intermolecular interactions that lead to molecular orientations optimally suited for second harmonic generation. The salt of AENA shows appreciable solid-state second harmonic generation whereas the control case of the pNA salt shows no measurable effect. This study highlights the utility of a remote functionality in steering the molecular assembly and achieving nearly the maximum second harmonic generation capability for the given nonlinear optical chromophore.

Discovery of Non-linear Optical Materials by Function-Based Screening of Multi-component Solids

“…27 In order to counter this preference for a centrosymmetric lattice and enhance its amenability toward salt and cocrystal formation, we have used the concept of ''remote functionalization,'' a synthetic process by which a flexible pendant group bearing remote functionality is attached to the parent NLO-phore to facilitate complexation with various coformers to steer achiral building blocks into a non-centrosymmetric environment. 28,29 Using this strategy, we appended an ethyl amine group to MNA, resulting in N-(2-aminoethyl)-4-nitro-2-anisidine (1; Figure 2). The terminal -NH 2 functionality is useful in salt and cocrystal formation, and the saturated ethyl bridge disengages the remote basic group from altering the b of the parent MNA chromophore.…”

Influence of Spiral Framework on Nonlinear Optical Materials

“…[18][19][20][21][22][23][24] An organic molecule with an electron donor (D) linked to an electron acceptor (A) through a p-conjugated bridge [25][26][27][28][29] (i.e. Among all the D-p-A frameworks, 4-nitroaniline [30][31][32] composed of a p-conjugated organic bridge (benzene) with an electron-donor amino (NH 2 ) group and an electron-acceptor nitryl (NO 2 ) group is well known in NLO research. Among all the D-p-A frameworks, 4-nitroaniline [30][31][32] composed of a p-conjugated organic bridge (benzene) with an electron-donor amino (NH 2 ) group and an electron-acceptor nitryl (NO 2 ) group is well known in NLO research.…”

“…D-p-A) is a classical class of NLO materials that exhibit large first hyperpolarizability. Among all the D-p-A frameworks, 4-nitroaniline [30][31][32] composed of a p-conjugated organic bridge (benzene) with an electron-donor amino (NH 2 ) group and an electron-acceptor nitryl (NO 2 ) group is well known in NLO research. In contrast, 4-nitrophenyldiphenylamine can be obtained not only by replacing the H atom at the 4-position of triphenylamine with a NO 2 group, but it can also be obtained by replacing the two H atoms of the NH 2 group in 4-nitroaniline with two phenyl groups.…”

Entry of chiral phthalimides with significant second order nonlinear optical and piezoelectric properties

“…5b The presence of one or more chiral centers in a molecule helps in developing the acentric structure and this strategy is employed to obtain novel acentric materials. 9 We have been interested in extending the concept of chirality in phthalimides with the aim of exploring their structural aspects and solid state properties. The presence of C-H … O hydrogen bonding in several phthalimides supported their great significance in crystal engineering and allowed the building of supramolecular-structures.…”