Syntheses and quadratic nonlinear optical properties of 2,7-fluorenylene- and 1,4-phenylene-functionalized o-carboranes.

o-Carboranes C-functionalized by (4-substituted-phen-1-yl)ethynyl-1,4-phenyl groups or (2-substituted-fluoren-7-yl)ethynyl-2,7-fluorenyl groups, in which the pendant functionalization is electron-withdrawing nitro or electron-donating diphenylamino groups, have been synthesized and in many cases structurally characterized. Diphenylamino-containing examples coupled via the two π-delocalizable bridges to the electron-accepting o-carborane unit exhibit the greater quadratic optical nonlinearities at 1064 nm (hyper-Rayleigh scattering, ns pulses), the nonlinearities also increasing on proceeding from 1,4-phenylene- to 2,7-fluorenylene-containing bridge. The most NLO-efficient example 2-(n-butyl)-1-(2-((9,9-di(n-butyl)-2-(N,N-diphenylamino)-9H-fluoren-7-yl)ethynyl)-9,9-di(n-butyl)-9H-fluoren-7-yl)-1,2-ortho-carborane, consisting of diphenylamino donor, fluorenyl-containing bridge, o-carborane acceptor, and solubilizing n-butyl units, exhibits large 〈β〉 (230 × 10 esu) and frequency-independent (two-level model) 〈β〉 (96 × 10 esu) values.

Photovoltaic Effect of a Ferroelectric-Luminescent Heterostructure under Infrared Light Illumination.

In this report, a ferroelectric-luminescent heterostructure is designed to convert infrared light into electric power. We use BiFeO (BFO) as the ferroelectric layer and YO:Yb,Tm (YOT) as the upconversion layer. Different from conventional ferroelectric materials, this heterostructure exhibits switchable and stable photovoltaic effects under 980 nm illumination, whose energy is much lower than the band gap of BFO.

Quadratic and cubic hyperpolarizabilities of nitro-phenyl/-naphthalenyl/-anthracenyl alkynyl complexes.

1-Nitronaphthalenyl-4-alkynyl and 9-nitroanthracenyl-10-alkynyl complexes [M](C[triple bond, length as m-dash]C-4-C10H6-1-NO2) ([M] = trans-[RuCl(dppe)2] (6b), trans-[RuCl(dppm)2] (7b), Ru(PPh3)2(η5-C5H5) (8b), Ni(PPh3)(η5-C5H5) (9b), Au(PPh3) (10b)) and [M](C[triple bond, length as m-dash]C-10-C14H8-9-NO2) ([M] = trans-[RuCl(dppe)2] (6c), trans-[RuCl(dppm)2] (7c), Ru(PPh3)2(η5-C5H5) (8c), Ni(PPh3)(η5-C5H5) (9c), Au(PPh3) (10c)) were synthesized and their identities were confirmed by single-crystal X-ray diffraction studies. Electrochemical studies and a comparison to the 1-nitrophenyl-4-alkynyl analogues [M](C[triple bond, length as m-dash]C-4-C6H4-1-NO2) ([M] = trans-[RuCl(dppe)2] (6a), trans-[RuCl(dppm)2] (7a), Ru(PPh3)2(η5-C5H5) (8a), Ni(PPh3)(η5-C5H5) (9a), Au(PPh3) (10a)) reveal a decrease in oxidation potential for ruthenium and nickel complexes on proceeding from the phenyl- to naphthalenyl- and then anthracenyl-containing bridge. HOMO → LUMO transitions characteristic of MC[triple bond, length as m-dash]C-1-C6H4 to 4-C6H4-1-NO2 charge transfer red-shift and gain in intensity on proceeding to the ruthenium complexes; the low-energy transitions have increasing ILCT character on proceeding from the phenyl- to naphthalenyl- and then anthracenyl-containing bridge.

Syntheses and Optical Properties of Azo-Functionalized Ruthenium Alkynyl Complexes.

The syntheses of trans-[Ru(C≡C-1-C H -4-N=N-1-C H -4-C≡C-1-C H -4-NO )Cl(L ) ] (L =dppm (Ru1), dppe) (Ru2)), trans-[Ru(C≡C-1-C H -4-N=N-1-C H -4-(E)-CH=CH-1-C H -4-NO )Cl(dppe) ] (Ru3), and trans-[Ru(C≡C-1-C H -4-(E)-CH=CH-1-C H -2,6-Et -4-N=N-1-C H -4-NO )Cl(dppe) ] (Ru4) are reported, together with those of precursor alkynes. Their electrochemical properties were assessed by cyclic voltammetry (CV), linear optical and quadratic nonlinear optical (NLO) properties assayed by UV/Vis-NIR spectroscopy and hyper-Rayleigh scattering studies at 1064 nm, respectively, and their linear optical properties in the formally Ru state examined by UV/Vis-NIR spectroelectrochemistry. These data were compared to those of analogues with E-ene and yne linkages in place of the azo groups.

Synthesis, Optical, Electrochemical, and Theoretical Studies of Dipolar Ruthenium Alkynyl Complexes with Oligo(phenylenevinylene) Bridges.

The syntheses of oligo(p-phenylenevinylene)s (OPVs) end-functionalized with a ligated ruthenium alkynyl unit as a donor and a nitro as acceptor, namely trans-[Ru{C≡C-1-C H -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -4-NO }Cl(dppe) ] (Ru4), trans-[Ru{C≡C-1-C H -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -2,5-(n-hexyl) -4-(E)-CH=CH-1-C H -2,5-(n-hexyl) -4-(E)-CH=CH-1-C H -4-NO }Cl(dppe) ] (Ru6), and trans-[Ru{C≡C-1-C H -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -2,5-Et -4-(E)-CH=CH-1-C H -2,5-(n-hexyl) -4-(E)-CH=CH-1-C H -2,5-(n-hexyl) -4-(E)-CH=CH-1-C H -2,5-(2-ethyl-n-hexyl) -4-(E)-CH=CH-1-C H -2,5-(2-ethyl-n-hexyl) -4-(E)-CH=CH-1-C H -4-NO }Cl(dppe) ] (Ru8), are reported, together with those of precursor alkynes. Their electrochemical properties were assessed by cyclic voltammetry (CV), their linear optical and quadratic nonlinear optical (NLO) properties assayed by UV/Vis-NIR spectroscopy and hyper-Rayleigh scattering studies at 1064 nm, respectively, and their linear optical properties in the formally Ru state examined by UV/Vis-NIR spectroelectrochemistry. Computational studies employing time-dependent density functional theory were undertaken on model complexes to rationalize the optical observations.

Record Multiphoton Absorption Cross-Sections by Dendrimer Organometalation.

Large increases in molecular two-photon absorption, the onset of measurable molecular three-photon absorption, and record molecular four-photon absorption in organic π-delocalizable frameworks are achieved by incorporation of bis(diphosphine)ruthenium units with alkynyl linkages. The resultant ruthenium alkynyl-containing dendrimers exhibit strong multiphoton absorption activity through the biological and telecommunications windows in the near-infrared region. The ligated ruthenium units significantly enhance solubility and introduce fully reversible redox switchability to the optical properties.

Synthesis and optical power limiting properties of heteroleptic Mo3S7 clusters.

Substitution of the halide ligands in (Bu4N)2[Mo3S7X6] (X = Cl, Br) by diimine ligands, such as 4,4'-dimethyl-2,2'-bipyridine (dmbpy), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), affords the neutral heteroleptic clusters Mo3S7Cl4(dmbpy) (), Mo3S7Br4(dmbpy) (), Mo3S7Br4(bpy) (), and Mo3S7Br4(phen) (). Further substitution of the halide ligands in Mo3S7Br4(diimine) clusters by dmit (1,3-dithiole-2-thione-4,5-dithiolate) allows the preparation of the mixed diimine-dithiolene neutral cluster complexes Mo3S7(dnbpy)(dmit)2 (, dnbpy = 4,4'-dinonyl-2,2'-bipyridine), Mo3S7(dcmbpy)(dmit)2 (, dcmbpy = 4,4'-dimethoxycarbonyl-2,2'-bipyridine), and Mo3S7(dcbpy)(dmit)2 (, dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid). The optical limiting properties of complexes have been assessed by the open-aperture Z-scan technique at 570 nm, employing a nanosecond optical parametric oscillator.

A hybrid ruthenium alkynyl/zinc porphyrin "Cross Fourchée" with large cubic NLO properties.

A new Zn(ii) porphyrin-cored ruthenium alkynyl dendrimer (2) containing twelve Ru(κ(2)-dppe)2 bis-alkynyl fragments has been prepared in two steps from 5,10,15,20-tetra(4-ethynylphenyl)porphyrinatozinc(ii) and shown to be highly active for third-harmonic generation (THG) at 1907 nm.

Experimental test of the Rayleigh-Debye-Gans theory for light scattering by fractal aggregates.

Calibrated measurements of optical (lambda = 488-nm) scattering cross sections, in the form of Rayleigh ratios, are presented for two fractal aggregate aerosols. The aggregates have radii of gyration of approximately 280 nm, fractal dimensions of approximately 1.75, and monomer sizes of approximately 20 nm with approximately 150 monomers per cluster.