Structural Modulation of the Dipolar−Octupolar Contributions to the NLO Response in Subphthalocyanines

Abstract

Second order nonlinear optical properties of a series of trinitrosubphthalocyanine (SubPc) isomers were studied experimentally by electric field induced second harmonic (EFISH) generation and hyper Rayleigh scattering (HRS). These experimental values were compared to the ones obtained theoretically employing both sum over states (SOS) and finite field (FF) methods. From these studies, it was shown that the dipolar contributions to the beta tensor are very much dependent on the substitution pattern at the periphery of the subphthalocyanine macrocycle, whereas the octupolar contributions remain mostly unchanged. Consequently, it was deduced that SubPc is extremely well suited for the decoupling of octupolar and dipolar contribution to the NLO response.

Variation of the Backbone Conjugation in NLO Model Compounds: Torsion‐Angle‐Restricted, Biphenyl‐Based Push‐Pull‐Systems

“…Especially on the molecular level, numerous publications document the very basic comprehension of structure-property relationships, in spite of the fact that great progress has been made in the last few years. [16,[21][22][23][24][25][26][27][28] Indeed, large π-conjugated systems with donor and acceptor groups have been synthesized with a high potential for large nonlinear optical effects. Despite the advances in chromophore design, a deeper comprehension of structural features governing the NLO properties is required to enable reliable theoretical predictions and thus, allowing an improved design of tailor-made NLO materials.…”

Density Functional Theory Study on Subtriazaporphyrin Derivatives: Dipolar/Octupolar Contribution to the Second-Order Nonlinear Optical Activity

“…12,13 More recently, multipolar, especially octupolar molecules have been developed as alternative NLO chromophores since these molecules do not possess a permanent dipole moment and therefore can easily form noncentrosymmetric bulk materials as required to obtain a large macroscopic 2 nd -NLO response. [19][20][21][22][23][24][25][26][27][28][29][30][31] In 2010, the structure, electronic distribution, molecular orbitals, infrared (IR) spectra, and electronic absorption spectra of a full series of low-symmetrical fluoroboron-subtriazaporphyrin (FB-SubTAP) derivatives were systematically investigated based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculation. Due to their distinct structural, optical, and electronic properties, the SubPc derivatives have attracted much research interests.…”

“…Due to their distinct structural, optical, and electronic properties, the SubPc derivatives have attracted much research interests. 20,[28][29][30][31] For example, Torres et al studied the NLO response of SubPcs with electron-donating or -accepting substituents at the peripheral positions. 27a In addition, as a typical octupolar molecule with 14-π electron aromatic structure, the 2 nd -NLO activities of SubPc and its analogues have been experimentally and theoretically investigated.…”

Synthesis of water-soluble subphthalocyanines

“…4 In contrast, little is known about their lower homologues, the subphthalocyanines 5 (SubPcs) comprising a 14 p-electron non-planar aromatic macrocycle made of three diiminoisoindole units N-fused around a central boron atom. SubPcs show very attractive photophysical and electrochemical properties, and are interesting for applications as chromophores in nonlinear optics, 6 in OLEDs, 7 in photovoltaic devices, 8 and in multicomponent donor-acceptor systems. 9 Synthesis of water-soluble subphthalocyanines still remains a particularly difficult task, 10 since many phthalonitriles successfully employed in phthalocyanine synthesis are incompatible with boron trihalides employed in their formation reaction.…”