Theoretical investigations into spectral and non-linear optical properties of brucine and strychnine using density functional theory

Pandith

2014

J Mol Model

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This work involved the design of a new series of triarylaminehelicenes (TAH) with significant hole transport capacity and enhanced nonlinear optical response. The geometries, electronic properties and nonlinear response of TAH derivatives were studied using density functional theory at the B3PW91/6-311++G (2d, 2p) level. Charge transfer and nonlinear optical response were analyzed and correlated with modifications in geometry and energy levels. Calculations indicated that trivial changes in the torsional angle occur in TAH derivatives with electron-donating substituents as compared to those with electron-withdrawing substituents, resulting in lower reorganization energies for TAH derivatives 2-6. TAH derivatives with an -N(CH3)2 group have the greatest highest occupied molecular orbital (HOMO) level, and thus the least ionization potential, indicating significant hole transfer efficiency as compared to unsubstituted TAH. A decrease in the HOMO-LUMO gap occurs upon substitution with electron-releasing groups, whereas there is an increase in the case of -NO2, -COOH, and -CN TAH derivatives. Topological analysis of the HOMOs of the neutral molecules revealed that these orbitals are concentrated mainly in the helicene backbone, with an important contribution from fused phenyl rings, nitrogen atoms and carbonyl groups. However, the lowest unoccupied molecular orbitals (LUMO) are invariably constituted by fused phenyl rings without any contribution from the central nitrogen atom. Studying the effect of substitution on the nonlinear optical response of TAH derivatives, the calculated polarizability and hyperpolarizability at B3PW91/6-311++G (2d,2p) level of theory exhibited a prominent improvement as compared to unsubstituted TAH. Both electron-donating groups and electron-withdrawing groups result in a red shift in the electronic absorption bands of the substitution derivatives, in particular those with -N(CH3)2 and -NH2 groups.

Section: Nonlinear Responsementioning

confidence: 99%

“…The total static dipole moment (μ), average linear polarizability (α) and first-order hyperpolarizability (β) using the x, y, z components of the compound from Gaussian 03 W [60] output were calculated by Eqs. 4-6 [61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77].…”

Section: Introductionmentioning

confidence: 99%

Optoelectronic and nonlinear optical properties of triarylamine helicenes: a DFT study

Pandith

2014

J Mol Model

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“…The B3PW91 functional was chosen based on numerous earlier studies which suggest it to be efficient and reasonably accurate in predicting ground and excited state energies of a broad range of organic molecules and inorganic complexes [38,42,43,61,62].…”

Section: Computational Detailsmentioning

confidence: 99%

Analysis of vibrational spectra (FT-IR and VCD) and nonlinear optical properties of [Ru(L)₃]²⁺ complexes

Journal of Coordination Chemistry

Pandith

2014

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Density functional theory calculations were performed on [Ru(L) 3 ] 2+ (L = 1,10-phenanthroline, 2,2′-bipyridine, 2,2′-bipyrimidine, 2,2′-bipyrazine) complexes by employing B3PW91 functional and LAN2DZ basis set to predict their spectra and nonlinear optical response. The geometrical and coordination energy studies explained that the stability of [Ru(L) 3 ] 2+ metal complexes depends on the extent of interaction of the dπ orbitals of Ru 2+ with the π* ligand orbitals, which is maximum for 1,10-phenanthroline. The two enantiomers of the [Ru(L) 3 ] 2+ show IR absorption peaks in the region of 1100-1800 cm −1 , and a slight shift occurs to lower frequency by solvent. The vibrational circular dichroism peaks of [Ru(phen) 3 ] 2+ had major contribution from out-of-phase stretching of 1,10-phenanthroline rings and a minor contribution from H-C=C-H wagging and C=C stretching of rings. Maximum hyperpolarizability was observed for [Ru(phen) 3 ] 2+ due to stronger anharmonicity in the π-electron system. Among the [Ru(L) 3 ] 2+ (L = bpy, bpm, and bpz) complexes, [Ru(bpm) 3 ] 2+ shows enhanced hyperpolarizability due to increase in the dipole along the X-direction. In derivative Ru 2+ complexes, we found that hyperpolarizability depends on electron-donating capability of the substituent. As per FMOs study, the HOMO is predominantly metal fragment based, the LUMO is primarily ligand based, and the larger value of hyperpolarizability corresponds to the lower E LUMO -E HOMO gap, reflecting that nonlinear optical response is a consequence of additive dipolar responses of charge transfer and hyperpolarizability.

“…A significant interest still exists for novel molecular materials with optimal NLO properties because of their primary roles in applications in fields including optical communications and computation, optical switching and limiting, data storage and retrieval, and sensors (Islam et al, 2014; Dadsetani and Omidi, 2015). The nonlinear response of molecules to electromagnetic fields has been studied over the last two decades.…”

Section: Introductionmentioning

confidence: 99%

Computational Studies on Optoelectronic and Nonlinear Properties of Octaphyrin Derivatives

Lone²

2017

Front. Chem.

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The electronic and nonlinear optical (NLO) properties of octaphyrin derivatives were studied by employing the DFT/TDFT at CAM-B3LYP/6-311++G (2d, 2p) level of the theory. Thiophene, phenyl, methyl and cyano moieties were substituted on the molecular framework of octaphyrin core, in order to observe the change in optoelectronic and nonlinear response of these systems. The frontier molecular orbital studies and values of electron affinity reveals that the studied compounds are stable against the oxygen and moisture present in air. The calculated ionization energies, adiabatic electron affinity and reorganization energy values indicate that octaphyrin derivatives can be employed as effective n-type material for Organic Light Emitting Diodes (OLEDs). This character shows an enhancement with the introduction of an electron withdrawing group in the octaphyrin framework. The polarizability and hyperpolarizability values of octaphyrin derivatives demonstrate that they are good candidates for NLO devices. The nonlinear response of these systems shows enhancement on the introduction of electron donating groups on octaphyrin moiety. However, these claims needs further experimental verification.