Light losses from scattering in luminescent solar concentrator waveguides.

The reductions in the transmission of emission originating from a fluorophore dissolved in a polymer matrix due to light scattering were compared in two forms of planar waveguides used as luminescent solar concentrators: a thin film of poly(methylmethacrylate) (PMMA) spin-coated on a glass plate and a solid PMMA plate of the same dimensions. The losses attributable to light scattering encountered in the waveguide consisting of the thin film of polymer coated on a glass plate were not detectable within experimental uncertainty, whereas the losses in the solid polymer plate were significant. The losses in the solid plate are interpreted as arising from light-scattering centers comprising minute bubbles of vapor/gas, incomplete polymerization or water clusters that are introduced during or after the thermally induced polymerization process.

The photophysics of phenylenevinylene oligomers and self-absorption of their fluorescence in polymer films.

The fluorescence spectra, quantum yields and lifetimes of a series of alkoxy-substituted phenylenevinylene molecules, which serve as short chain oligomer models for poly(p-phenylenevinylene), have been determined in fluid solvents and in a high viscosity polymer matrix. The effects of solvent polarity and a high viscosity molecular environment on the fluorescence yields and spectral shapes have been established. Alkoxy group substitution on the phenyl ring moieties of the molecules has an important effect on the vibronic structures and profiles of the absorption spectra.

1-(2,3-Di-hydroxy-prop-yl)-4-{2-[4-(di-methyl-amino)-phen-yl]vin-yl}pyridinium chloride.

The title compound, C18H23N2O2 (+)·Cl(-), crystallizes with two independent cations and anions per cell. Each cation has twofold rotational disorder about the linking vinyl groups but with unequal occupancies [0.963 (5):0.

2-(3-Cyano-4-{3-[1-(2-hy-droxy-eth-yl)-3,3-dimethyl-1,3-di-hydro-indol-2-yl-idene]prop-2-en-yl}-5,5-dimethyl-5H-furan-2-yl-idene)malono-nitrile.

The title compound, C25H24N4O2, adopts a cisoid configuration and has twofold orientational disorder of the 2-hy-droxy-ethyl group. The mol-ecule is twisted from planarity so that the dihedral angle between the terminating indol-2-yl-idene and the furan-2-yl-idene moiety mean planes is 12.75 (7)°.

2-{2-[5-(4-Cyano-5-di-cyano-methyl-idene-2,2-dimethyl-2,5-di-hydro-furan-3-yl)penta-2,4-dienyl-idene]-3,3-dimethyl-2,3-di-hydro-1H-indol-1-yl}ethyl 3,5-bis-(benz-yloxy)benzoate.

In the title mol-ecule, C48H42N4O5, a potential non-linear optical compound, the furan ring [r.m.s.

1-(4-{[(1,3,3-Tri-methyl-indolin-2-yl-idene)meth-yl]diazen-yl}phen-yl)ethanone.

The title compound, C20H21N3O, has crystallographic mirror symmetry with all non-H atoms apart from the methyl C atom of the CMe2 group lying on the mirror plane. Mol-ecules are linked into planar sheets parallel to (010) by phen-yl-azo C-H⋯N and phen-yl-ethanone C-H⋯O inter-actions. Methyl C-H⋯π inter-actions provide crosslinking between the planes.

4-Methyl-5-(4-nitro-benzyl-idene)-2-oxo-2,5-di-hydro-1H-pyrrole-3-carbo-nitrile.

Mol-ecules of the potential non-linear optical title compound, C13H9N3O3, form dimeric stacks of mol-ecules along the a axis cross-linked around inversion centers by N-H⋯O hydrogen bonds and weak (phen-yl)C-H⋯O inter-molecular inter-actions, forming a 'collaboration' of R 2 (2)(8) and R 2 (2)(16) ring motifs. The mol-ecules are then further linked by weak C-H⋯O and C-H⋯N inter-actions into sheets parallel to (121).

Bis(2-carb-oxy-N-{[1-(2-hy-droxy-eth-yl)-3,3-dimethyl-indolin-2-yl-idene]methyl-imino}-anilinium) sulfate monohydrate.

The asymmetric unit of the title compound, 2C20H22N3O3(+)·SO4(2-)·H2O, contains four cations, two sulfate anions and two lattice water mol-ecules. One of the four cations shows a different conformation of the hy-droxy-ethyl group; the remaining three are all essentially superimposable. Two cations exhibit two-site orientational disorder [ratios = 0.

2-[4-(2-{5-tert-Butyl-2-chloro-3-[2-(3-pentyl-1,3-benzothia-zol-2-yl-idene)ethyl-idene]cyclo-hex-1-en-yl}ethen-yl)-3-cyano-5,5-dimethyl-furan-2-yl-idene]malono-nitrile.

In the title mol-ecule, C36H39ClN4OS, the non-aromatic part of the cyclo-hex-1-enyl ring and the attached tert-butyl group are disordered over two conformations with occupancy ratios of 0.52 (3):0.48 (3) and 0.

(E)-5-[3-Cyano-2-(dicyano-methyl-ene)-1-oxaspiro-[4.5]dec-3-en-4-yl]-3-(1-methyl-1,4-dihydro-pyridin-4-yl-idene)pent-4-en-1-yl 3,5-bis-(benz-yloxy)benzoate.

In the title compound, C45H40N4O5, the cyclo-hexane entity on the (3-cyano-2,5-dihydro-furan-2-yl-idene)propane-dinitrile group, which replaces the usual dimethyl substituents, has not perturbed the delocalization geometry significantly. Weak inter-molecular inter-actions, viz. C-H⋯N(cyano), C-H⋯O(ether), C-H⋯π and π-π [between the aromatic rings with the shortest centroid-centroid distance of 3.

2-{3-Cyano-4-[2-(4-diethylamino-2-hy-droxyphenyl)ethenyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile acetone 0.25-solvate.

In the title compound, C(22)H(22)N(4)O(2)·0.25C(3)H(6)O, the disordered acetone mol-ecule lies with partial occupancy about the 2 axis. The mol-ecule of the malononitrile derivative is essentially planar excluding the methyl groups, with the largest deviation from the mean plane through the non-H atoms being 0.

Testing computational models of hyperpolarizability in a merocyanine dye using spectroscopic and DFT methods.

The structural and electronic properties of a highly solvatochromic merocyanine dye, 2-(3-cyano-5,5-dimethyl-4-(3-(1-octadecylpyridin-4(1H)-ylidene)prop-1-enyl)furan-2(5H)-ylidene)malononitrile (pyr3pi), have been investigated using UV-vis, NMR, hyper-Rayleigh scattering, and Raman spectroscopies and further interpreted using computational chemistry. Spectroscopic data indicate that pyr3pi exists in its zwitterionic form even in low polarity solvents with electronic absorption spectra showing a hypsochromic shift with an increase in solvent polarity and NMR experiments indicating an increasingly zwitterionic structure in chloroform as the temperature is lowered. Raman spectra in increasingly polar solvents show small variations of the structure that are consistent with a change toward a structure with more zwitterionic character.

C-H⋯π packing inter-actions in 2-[5,5-bis-(4-benzyl-oxyphen-yl)-3-cyano-4-methyl-2,5-dihydro-furan-2-yl-idene]malononitrile.

The title mol-ecule, C(35)H(25)N(3)O(3), packs utilizing C-H⋯π attractive inter-actions causing the identical 4-benzyl-oxyphenyl groups to pack with different conformational angles. This difference is consistent with the variable inter-planar dihedral angles found in closely related structures.

2-(3-Cyano-4-{7-[1-(2-hy-droxy-eth-yl)-3,3-dimethyl-indolin-2-yl-idene]hepta-1,3,5-trien-yl}-5,5-dimethyl-2,5-dihydro-furan-2-yl-idene)malononitrile.

The title compound, C(29)H(28)N(4)O(2), excluding the hydroxyethyl and methyl groups, is slightly twisted from planarity so that the terminating indol-2-yl-idene and furan-2-yl-idene moiety planes subtend a dihedral angle of 6.27 (8)°. A small inwards fold in the polymethine atom chain is consistent with centrosymmetric dimer formation via O-H⋯N(cyano) hydrogen bonds.

4-tert-Butyl-2-[2-(1,3,3-trimethyl-indolin-2-yl-idene)ethyl-idene]cyclo-hexa-none.

The title mol-ecule, C(23)H(31)NO, has two alternative cyclo-hexa-none configurations at the 4-position in a ratio of 0.663 (3):0.337 (3).

2-{[(Biphenyl-2-yl)diazen-yl]methyl-idene}-1,3,3-trimethyl-indoline.

The title mol-ecule, C(24)H(23)N(3), shows some delocalization of charge based on the small [8.0 (2)°] angle between the indolin-2-yl-idene ring system and the link methyl-diazene C(2)N(2) atom plane. A further twist of 17.

4-aminopyridinium 2-(anthracen-9-yl)-3-oxo-3H-inden-1-olate monohydrate.

The title compound, 2C(5)H(7)N(2)(+)·2C(23)H(13)O(2)(-)·H(2)O, formed as a by-product in the attempted synthesis of a nonlinear optical candidate molecule, contains two independent 4-aminopyridinium cations and 2-(anthracen-9-yl)-3-oxo-3H-inden-1-olate anions with one solvent water molecule. This is the first reported structure containing these anions. The two anions are not planar, having different interplanar angles between the anthracenyl and inden-1-olate moieties of 59.

2-(4-{3-[1-(3-Bromo-prop-yl)-3,3-dimethyl-2,3-dihydro-1H-indol-2-yl-idene]prop-1-en-yl}-3-cyano-5,5-dimethyl-2,5-dihydro-furan-2-yl-idene)malononitrile.

The backbone of the title mol-ecule, C(26)H(25)BrN(4)O, is approximately planar: the dihedral angle between the planes of the indoline ring system and the furan ring is 7.68 (14)°. In the crystal, layers lying parallel to (10) occur, with the mol-ecules inter-acting via weak C-H⋯N(cyano) and C-H⋯Br bonds and short N(cyano)⋯Br contacts [3.

5-(4-Cyano-5-dicyano-methyl-ene-2,2-dimethyl-2,5-dihydro-3-fur-yl)-3-(1-methyl-1,4-dihydro-pyridin-4-yl-idene)pent-4-enyl 3,5-bis-(benz-yloxy)benzoate acetonitrile 0.25-solvate: a synchrotron radiation study.

The title compound, C(42)H(36)N(4)O(5)·0.25CH(3)CN, crystallizes with a partial twofold disordered (1/4) acetonitrile solvent of crystallization. The linking atoms to the 3,5-bis-(benz-yloxy)benzoic acid are disordered between two conformations in the ratio 0.

Geometry and bond-length alternation in nonlinear optical materials. III. Structural parameters of two chromophores containing aromatizable donorsPart II: Gainsford, Bhuiyan & Kay (2008a).

The planar component of 2-{3-cyano-4-[3-(1-decyl-1,4-dihydroquinolin-4-ylidene)prop-1-enyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile, C(32)H(46)N(4)O, (I), forms into layers parallel to the (\overline{1}01) plane. The larger of the two spaces between layers is filled by the alkyl chains, giving a ;sandwich stack' appearance. The packing of 2-{3-cyano-4-[5-(1-decyl-1,4-dihydroquinolin-4-ylidene)penta-1,3-dienyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile, C(34)H(38)N(4)O, (II), which has partial disorder in the 1-decyl group, utilizes weak C-H.

Geometry and bond-length alternation in nonlinear optical materials. II. Effects of donor strength in two push-pull molecules.

The compounds N-[2-(4-cyano-5-dicyanomethylene-2,2-dimethyl-2,5-dihydrofuran-3-yl)vinyl]-N-phenylacetamide, C(20)H(16)N(4)O(2), (I), and 2-{3-cyano-5,5-dimethyl-4-[2-(piperidin-1-yl)vinyl]-2,5-dihydrofuran-2-ylidene}malononitrile 0.376-hydrate, C(17)H(18)N(4)O x 0.376 H(2)O, (II), are novel push-pull molecules.

Bis[4-(dimethyl-amino)phen-yl]diazene oxide.

The asymmetric unit of the title compound, C(16)H(20)N(4)O, contains six independent approximately planar mol-ecules and is best described as a commensurate modulation of a P2(1)/c parent. Two sets of disordered mol-ecules share almost the same locations (related by an in-plane translation), ensuring that the c-glide plane condition is not attained. C-H⋯O inter-actions provide structural cohesion.

2-{3-Cyano-5,5-dimethyl-4-[4-(pyrrol-idin-1-yl)buta-1,3-dien-yl]-2,5-dihydro-furan-2-yl-idene}malononitrile dichloro-methane solvate.

The structure of the title compound, C(18)H(18)N(4)O·CH(2)Cl(2), was solved using data collected from a multiple crystal (note high R factors). The crystal structure is dominated by two bifurcated attractive C-H⋯N(cyano) inter-actions.

2-{3-Cyano-5,5-dimethyl-4-[4-(piperidin-1-yl)buta-1,3-dien-yl]-2,5-dihydro-furan-2-yl-idene}malononitrile.

The title compound, C(19)H(20)N(4)O, crystallizes as twinned crystals containing two independent mol-ecules which pack into a three-dimensional matrix via several C-H⋯N(cyano) inter-actions, with a C⋯N range of 3.324 (8)-3.568 (8) Å and C-H⋯N angles in the range 147-166°.

2-{3-Cyano-5,5-dimethyl-4-[6-(pyrrol-i-din-1-yl)hexa-1,3,5-trien-yl]-2,5-dihydro-2-furylidene}malononitrile.

The title compound, C(20)H(20)N(4)O, is packed into a three-dimensional 'herringbone' matrix using two different types of attractive C-H⋯N(cyano) inter-actions. The bond-length alternation, caused by delocalization of charge between the donor N atoms and the cyano acceptor groups, is compared with related compounds.