title: A new type of organic-inorganic hybrid NLO-phore with large off-diagonal first hyperpolarizability tensors: a two-dimensional approach.
abstract: We report a novel type of organic-inorganic hybrid material with rare two-dimensional nonlinear optical (NLO) properties. The density functional theory (DFT) calculations combined with the finite-field (FF) method show that the designed molecules (6,9 organo-derivatives of B10H14) could carry the characteristic NLO properties of both organic and inorganic materials. Interestingly, due to their unique V-shaped structures, they have large off-diagonal first hyperpolarizability tensors or nonlinear anisotropy, which is an advantage in their practical applications over conventional donor-π-acceptor (D-π-A) NLO-phores. The systematic substitutions of terminal donor/acceptor groups as well as the extension of π-conjugation along the V-shape in these derivatives have been evaluated to guide a purpose-oriented synthesis of NLO material. All the systems in the present study have been categorized into Set-I and Set-II with D-π-A-π-D and A-π-D-π-A configurations, respectively. These designed derivatives show large amplitudes of βz values. For example, systems 3N (6,9-[(N=C=Ph-NO2)2]-B10H12) and 4N (6,9-[((N=C=Ph)2-NO2)2]-B10H12) have βz amplitudes as large as 34.16 and 276.91 × 10(3) a.u. which are 380 and 3000 times larger than those of a typical NLO molecule of urea, respectively. Remarkably, the substitution of nitrogen atoms with 6,9 hydrogen atoms in decaborane is shown to cause a lone pair back donation to vacant p orbitals of 6,9 boron atoms of the decaborane basket. This p orbital overlapping verticalizes the V-arms of the decaborane derivatives and boosts their nonlinear anisotropies due to their larger off-diagonal tensor components. The nonlinear anisotropy values are significantly larger, ranging from 1 (minimum in system 1) to 31.90 (maximum in system 3A) due to their unique V-shape. Comparison of their efficiencies with standard molecules demonstrates that our designed organic-inorganic hybrid molecules have significant potential as excellent candidates for NLO applications.
authors.affiliation: Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University Toyonaka, Osaka 560-8531, Japan. mnaka@cheng.es.osaka-u.ac.jp shabbir193rb@gmail.com.
authors.forename: Shabbir
authors.initials: S
authors.lastname: Muhammad
authors.forename: Hongliang
authors.initials: H
authors.lastname: Xu
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Su
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukuda
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kishi
authors.forename: Yasuteru
authors.initials: Y
authors.lastname: Shigeta
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakano