Intrinsic hyperpolarizability of 3-dicyanomethylene-5,5-dimethyl-1-[2-(4-hydroxyphenyl)ethenyl]-cyclohexene nanocrystallites incorporated into the photopolymer matrices

Mixed ligand cobalt and palladium complexes containing triphenylphosphine and a hydrazone: Synthesis and application in non-linear optics

Mixed ligand complexes of cobalt and palladium containing triphenylphosphine and a hydrazone derived from furfural and hydrazine hydrate have been designed, synthesized, evaluated, and characterized from their spectral properties, elemental analysis, and magnetic susceptibility measurements. The spectral techniques suggest that the complexes exhibit square planar geometry. The monomeric properties of the complexes are evaluated from their magnetic susceptibility values. The complexes were subjected to z-scan analysis for third-order non-linear optical measurements. Non-linear transmission measurements performed using laser pulses at 532 nm in nanosecond indicate that the complexes may show good potential as optical limiters.

One-photon Absorption Characterizations, Dipole Polarizabilities and Second Hyperpolarizabilities of Chlorophyll a and Crocin

The dispersion-free dipole polarizability (α) computations for chlorophyll a (1) and crocin (2) have been achieved by density functional theory (DFT) at B3LYP/ 6-31G(d) level. The measured one-photon absorption (OPA) wavelengths are quite consistence with the theoretically obtained values. Ab-initio quantum chemical calculations (time-dependent Hartree-Fock (TDHF)) have been implemented to reveal the static second hyperpolarizabilities (γ) and dynamic dipole polarizabilities of the title molecules. The examined compounds display γ with non-zero values, introducing their third-order nonlinear optical (NLO) phenomena. The first and second frontier molecular orbitals of the investigated molecules have been also derived from DFT.

N→Sn-Coordinated Stannaoxidoborates Containing a SnB4O6 Unit

We report here the synthesis of new N→Sn-coordinated stannaoxidoborates H[LSnB4O6R4] {L = [2,6-(Me2NCH2)C6H3](-) and R = Ph (6), 4-Br-Ph (7), 3,5-(CF3)2-Ph (8), and 4-CHO-Ph (9)} containing a nonsymmetric SnB4O6 unit. Compounds 6-9 represent new derivatives of the pentaborates [B5O6R4](-) in which the central boron is substituted by a tin atom. Compounds 6-9 were characterized by means of elemental analysis, electrospray ionization mass spectrometry, and NMR spectroscopy and in the case of 6-8 also by single-crystal X-ray diffraction analysis. The structures of N→Sn-coordinated stannaoxidoborates 6-8 consist of a spirobicyclic arrangement, with two six-membered SnB2O3 rings at the tin atom providing the new stannaoxidoborate [LSnB4O6R4](-) motif, which is compensated for by the proton atom coordinated to the Me2N group of the ligand L. The linear and thermal properties of 6-9 were studied with the help of electronic absorption spectra and differential scanning calorimetry. In addition, the presence of the nonsymmetric stannaoxidoborate SnB4O6 unit in 6, 7, and 9 prompted us to investigate their second-order nonlinear-optical properties.

Synthesis, crystal structure, and spectroscopic properties of new stilbazolium salt with enlarged π-conjugated system

A new stilbazolium dye 4-{(E)-2-[4-(dimethylamino)naphthalen-1-yl]ethenyl}-1-methylquinolinium iodide monohydrate (DANSQI) having enlarged π-conjugated system was synthesized and characterized by X-ray diffraction, IR, Raman, UV-Vis, Fluorescence, (1)H- and (13)C NMR spectroscopy. Quantum chemical calculations were performed to obtain electronic structure and vibrational data, using DFT. The crystals are monoclinic, space group P21/n, with a=8.0751(14), b=25.839(4), c=10.9031(15) Å, V=2141.4(6) Å(3), and Z=4 (at 300(2) K). The unit cell contains four molecules of the dye, participating in weak intermolecular interactions. The cation is nearly flat with a deviation of the planarity of 5.08 (1)°. The dye investigated is the first stilbazolium iodide containing water molecule in the solid state therefore the N-dimethylamino group declines significantly from planarity, as indicated by C13N1C2C3 torsion angle of 16.08°. The dye studied shows solvatochromism of 84 nm in visible region and very large Stokes shift up to 253 nm. The intensity of fluorescence bands strongly depends on solvent polarity.

Nonlinear optical response of a polymer electret with incorporated organic chromophores

An analytical approach aimed at modeling the nonlinear optical (NLO) response of a polymer electret with incorporated organic dipole chromophores is extended to the dynamic case. The approach allows the effect of the locally anisotropic, polarizable, deformable polymer matrix on the chromophore NLO response to be accounted for. The method exploits the original cavity ansatz according to which the virtual cavity occupied by the chromophore in the polymer matrix is chosen to be conformal to the characteristic ellipsoid of the generalized permittivity tensor. Analytical expressions for the dynamic electric moments of dipole chromophores and macroscopic polarization of a polymer electret at fundamental and second harmonic frequencies are obtained by using a computational scheme based on two self-consistency procedures. On the basis of the expressions for dynamic macroscopic polarization, the analytical formulas for linear, chi(j)(i(1)) (omega), and quadratic, chi(jk)(i(2)) (2omega), electric susceptibilities are obtained. The presented expressions establish the relationship between the molecular polarizabilities of chromophores and the macroscopic electrical properties of the polymer electret.

Optimizing the hyperpolarizability tensor using external electromagnetic fields and nuclear placement

We investigate the effects of an external electric and magnetic field on the first hyperpolarizability tensor of a quantum system, such as a molecule or nanoparticle, whose nonlinear response is well below the fundamental limit. We find that the intrinsic hyperpolarizability is optimized when the applied electric and magnetic fields are comparable to the internal molecular fields. Indeed, the nonlinear response is just as large for an electron in the presence of the external field without the nuclei as it is for an electron bound to a molecule and in the presence of the applied field. We find that all combinations of fields and molecular structures that optimize the largest diagonal component of the intrinsic hyperpolarizability share the same universal properties: The three-level ansatz is obeyed, the normalized transition moment to the dominant state is about 0.76, the ratio of the two dominant excited state energies is about 0.48, the electron density tends toward being one-dimensional, and the intrinsic hyperpolarizability is less than 0.71. Thus, strategies for optimizing the hyperpolarizability should focus on ways to achieve these universal properties. On the other hand, when beta(xxy) is optimized, the three level ansatz appears to hold for a pair of degenerate states. In this case, the energy ratio between the pairs of degenerate states is 0.42 and the normalized transition moment to the pair of dominant states is 0.87. Most importantly, the intrinsic hyperpolarizability is 0.9, the largest ever calculated for a system described by a potential energy function.

Novel organic material with potential NLO application - electronic and spectroscopic properties

Novel dicyanoisophorone derivative, (E)-2-(3-(4-aminostyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile, is synthesized and its structure elucidated by means of conventional and linear polarized IR-spectroscopy of oriented colloids in nematic host, 1H, 13C, 1H, 1H-COSY NMR, HPLC tandem ESI MS-MS spectrometry, UV-VIS and thermal methods. Ab initio and DFT level of theory are used to theoretically obtain the electronic structure and optical properties, both in ground and exited state, of the compound.