Quadratic Nonlinear Optical Properties of N-Aryl Stilbazolium Dyes**

Trans-4'-(dimethylamino)-N-R-4-stilbazolium hexafluorophosphate (R = Me, Me 1, Ph, Ph 2, 2,4-dinitrophenyl, DNPh 3, 2-pyrimidyl, Pym 4, Scheme 1) were prepd. Their electronic absorption spectra show intense, visible intramol. charge-transfer bands, the energy (Emax) of which decreases in the order R = Me > Ph > DNPh > Pym. This trend arises from the steadily increasing electron deficiency of the pyridinium ring, a phenomenon also obsd. in cyclic voltammetric and 1H NMR data. Fluorescence-free 1st hyperpolarizability .beta. values of [1-4]PF6 were measured by using femtosecond hyper-Rayleigh scattering (HRS) with MeCN solns. and a 1300. nm laser, and static 1st hyperpolarizabilities .beta.0 were obtained by application of the two-state model. The HRS results indicate that the N-aryl chromophores in [2-4]PF6 have considerably larger .beta.0 values than their N-Me counterpart in [1]PF6, with a .apprx. 10-fold increase in .beta.0 obsd. in moving from [1]PF6 to [4]PF6 (25 .fwdarw. 230 .times. 10-30 esu). Stark (electroabsorption) spectroscopic studies in butyronitrile glasses at 77 K allowed the derivation of dipole moment changes .DELTA..mu.12 (10.9-14.8 D), which were used to calc. .beta.0 according to the two-state equation .beta.0 = 3.DELTA..mu.12(.mu.12)2/2(Emax)2 (.mu.12 = transition dipole moment). With the exception of [1]PF6, the Stark-derived .beta.0 values are in reasonable agreement with those from HRS. However, the increase in .beta.0 in moving from [1]PF6 to [4]PF6 is only 2-fold for the Stark data (90 .fwdarw. 185 .times. 10-30 esu). The obsd. trend of increasing .beta.0 in the order [1]PF6 < [3]PF6 < [2]PF6 < [4]PF6 arises from a combination of decreasing Emax and increasing .DELTA..mu.12, with only a slight increase in .mu.12 between [1]PF6 and [4]PF6. Probably the .beta.0 values for [3]PF6 are lower than expected due to the steric effect of the ortho-NO2 group, which causes twisting of the DNPh ring out of the plane of the stilbazolium unit. A single crystal x-ray structure shows that [2]PF6 crystallizes in the space group Cc, with head-to-tail alignment and almost parallel stacking of the pseudo-planar stilbazolium portions of the cations to form polar sheets within a polar bulk structure. [2]PF6 is essentially isostructural with the related Schiff base salt trans-4-[(4-dimethylaminophenyl)iminomethyl]-N-phenylpyridinium hexafluorophosphate ([8]PF6). Second harmonic generation (SHG) studies on [2]PF6 and [8]PF6 using a 1907. nm laser and sieved powd. samples (53-63 .mu.m) afforded efficiencies of 470 and 240 times that of urea, resp. Under the same conditions, the well-studied compd. [1]p-MeC6H4SO3 gave an SHG efficiency of 550 times that of urea. [on SciFinder (R)]

[1]  Peter Günter,et al.  Crystal growth and characterization of the organic salt 4-N, N-dimethylamino-4′-N-methyl-stilbazolium tosylate (dast) , 1996 .

[2]  M. C. Flipse,et al.  The determination of first hyperpolarizabilities β using hyper-Rayleigh scattering : a caveat , 1995 .

[3]  C. H. Wang,et al.  HYPER-RAYLEIGH SCATTERING USING 1907 NM LASER EXCITATION , 1999 .

[4]  R. G. Denning,et al.  Measurement of first hyperpolarizabilities by hyper‐Rayleigh scattering , 1996 .

[5]  O.F.J. Noordman,et al.  Time-resolved hyper-Rayleigh scattering: measuring first hyperpolarizabilities β of fluorescent molecules , 1996 .

[6]  T. Gelbrich,et al.  trans-4-[4-(Dimethylamino)phenyl-iminomethyl]-N- phenylpyridinium hexafluorophosphate , 2000 .

[7]  Hiromasa Ito,et al.  ORGANIC NONLINEAR OPTICAL CRYSTAL DAST GROWTH AND ITS DEVICE APPLICATIONS , 1999 .

[8]  K. Wostyn,et al.  High-frequency demodulation of multiphoton fluorescence in long-wavelength hyper-Rayleigh scattering. , 1999, Optics letters.

[9]  X. Duan,et al.  Second-Order Hyperpolarizabilities of Organic Ionic Species , 1995 .

[10]  P. Günter,et al.  Stilbazolium based zwitterionic chromophores for electro-optic polymers , 1997 .

[11]  C. M. Hudson.  Synthesis and mesomorphic properties of some asymmetrical pyrimidinylphenyldiacetylenes , 1999 .

[12]  Koen Clays,et al.  Enhancement of the molecular hyperpolarizability by a supramolecular amylose–dye inclusion complex, studied by hyper-Rayleigh scattering with fluorescence suppression , 1998 .

[13]  S. K. Kurtz,et al.  A Powder Technique for the Evaluation of Nonlinear Optical Materials , 1968 .

[14]  Jianhua Xu,et al.  Electric field induced molecular reorientation in stilbazolium salt Langmuir-Blodgett monolayers , 1998 .

[15]  K. Nakatani,et al.  From Intercalation to Aggregation: Nonlinear Optical Properties of Stilbazolium Chromophores−MPS3 Layered Hybrid Materials , 1996 .

[16]  K. McCallion,et al.  Waveguide fabrication and high-speed in-line intensity modulation in 4- N,N-4'-dimethylamino-4'-N'-methyl-stilbazolium tosylate , 1999 .

[17]  S. Boxer,et al.  Stark spectroscopy: applications in chemistry, biology, and materials science. , 1997, Annual review of physical chemistry.

[18]  Persoons,et al.  Hyper-Rayleigh scattering in solution. , 1991, Physical review letters.

[19]  A. Abbotto,et al.  Push–Pull Organic Chromophores for Frequency‐Upconverted Lasing , 2000 .

[20]  Koen Clays,et al.  Second-order nonlinear optical materials: recent advances in chromophore design , 1997 .

[21]  J. Oudar,et al.  Structural dependence of nonlinear-optical properties of methyl-(2,4-dinitrophenyl)-aminopropanoate crystals , 1982 .

[22]  J. Perry,et al.  Synthesis of organic salts with large second-order optical nonlinearities. , 1994, Science.

[23]  G. Ashwell,et al.  Improved second-harmonic generation from Langmuir–Blodgett films of hemicyanine dyes , 1992, Nature.

[24]  Joseph Zyss,et al.  Relations between microscopic and macroscopic lowest-order optical nonlinearities of molecular crystals with one- or two-dimensional units , 1982 .

[25]  J. Perry,et al.  Studies of the Electronic Structure of Metallocene-Based Second-Order Nonlinear Optical Dyes , 1999 .

[26]  Paul A. Fleitz,et al.  Nonlinear Optics of Organic Molecules and Polymers , 1997 .

[27]  C. Bosshard,et al.  Organic Nonlinear Optical Materials , 2001, CLEO/Europe Conference on Lasers and Electro-Optics.

[28]  Joseph Zyss,et al.  Nonlinear optical properties of organic molecules and crystals , 1987 .

[29]  J. Hupp,et al.  Probing the symmetry of the nonlinear optic chromophore Ru(trans-4,4'- diethylaminostyryl-2,2'-bipyridine)32+: Insight from polarized hyper- Rayleigh scattering and electroabsorption (Stark) spectroscopy , 1999 .

[30]  Nam Woong Song,et al.  Improved method for measuring the first-order hyperpolarizability of organic NLO materials in solution by using the hyper-Rayleigh scattering technique , 1996 .

[31]  R. Blessing,et al.  An empirical correction for absorption anisotropy. , 1995, Acta crystallographica. Section A, Foundations of crystallography.

[32]  S. Boxer,et al.  Effective Charge Transfer Distances in Cyanide-Bridged Mixed-Valence Transition Metal Complexes , 1998 .

[33]  Benjamin J. Coe,et al.  Enhancement of Molecular Quadratic Hyperpolarizabilities in Ruthenium(II) 4,4‘-Bipyridinium Complexes by N-Phenylation , 1998 .

[34]  Akira Watanabe,et al.  Fourier analysis of the femtosecond hyper-Rayleigh scattering signal from ionic fluorescent hemicyanine dyes , 2000 .

[35]  T. King,et al.  Efficient second-harmonic generation from all-polymeric Langmuir-Blodgett “AB” films containing up to 600 layers , 1994 .

[36]  Joseph Zyss,et al.  On the second-order polarizability of conjugated .pi.-electron molecules with octupolar symmetry: the case of triaminotrinitrobenzene , 1992 .

[37]  J. Abe,et al.  Manipulation of Dipole Moment and Hyperpolarizability Based on Heterocyclic Pyridinium Betaine Structures: Ab Initio and INDO/S MO Calculations , 1997 .

[38]  Eric Hendrickx,et al.  Hyper-Rayleigh Scattering in Isotropic Solution , 1998 .

[39]  Paras N. Prasad,et al.  Studies of two-photon pumped frequency-upconverted lasing properties of a new dye material , 1997 .

[40]  Tobin J. Marks,et al.  Chromophoric Self-Assembled Superlattices , 1996 .

[41]  Grant Bourhill,et al.  Problems Associated with Hyper-Rayleigh Scattering as a Means To Determine the Second-Order Polarizability of Organic Chromophores , 1996 .

[42]  H. Gornitzka,et al.  Chiral Stilbazolium Chromophores: An Approach toward Multiproperty Materials Combining Conductivity and Second-Order Optical Nonlinearities , 1999 .

[43]  Joseph T. Hupp,et al.  Electronic Stark Effect Studies of a Porphyrin-Based Push−Pull Chromophore Displaying a Large First Hyperpolarizability: State-Specific Contributions to β , 1998 .

[44]  R. W. Terhune,et al.  Measurements of Nonlinear Light Scattering , 1965 .

[45]  C. H. Wang,et al.  HYPER-RAYLEIGH SCATTERING MEASUREMENTS OF NONLINEAR OPTICAL CHROMOPHORES AT 1907 NM , 1997 .

[46]  J. Hupp,et al.  Electroabsorption Studies of Metal-to-Ligand Charge Transfer in Ru(phenanthroline)(3)(2+): Evidence for Intrinsic Charge Localization in the Initially Formed Excited State. , 1997, Inorganic chemistry.

[47]  H. Mao,et al.  LASERS, OPTICS, AND OPTOELECTRONICS 635 Single-pass thin-film electro-optic modulator based on an organic molecular salt , 1999 .

[48]  Koen Clays,et al.  High-frequency demodulation of multi-photon fluorescence in hyper-Rayleigh scattering , 1998 .

[49]  G. Ashwell,et al.  Organic Materials for Non-Linear Optics , 1989 .

[50]  Seth R. Marder,et al.  Synthesis of Organic Salts with Large Second-Order Optical Nonlinearities , 1989, Science.

[51]  Inge Asselberghs,et al.  Tuning of charge-transfer absorption and molecular quadratic non-linear optical properties in ruthenium(II) ammine complexes† , 1999 .

[52]  Peter Günter,et al.  Parametric-Interactions in the Organic Salt 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium Tosylate at Telecommunication Wavelengths , 1998, CLEO/Europe Conference on Lasers and Electro-Optics.

[53]  R. Blessing.  Outlier Treatment in Data Merging , 1997 .

[54]  J. Zyss,et al.  Stilbazolium-MPS3 Nanocomposites with Large Second-Order Optical Nonlinearity and Permanent Magnetization , 1994, Science.

[55]  E. Rivière,et al.  Structure and NLO Properties of Layered Bimetallic Oxalato-Bridged Ferromagnetic Networks Containing Stilbazolium-Shaped Chromophores , 2000 .

[56]  Peter Günter,et al.  DAST a high optical nonlinearity organic crystal , 2000 .

[57]  A new class of second-order non-linear optical material:stilbazolium benzimidazolate covalently bound to polymer backbone , 1997 .

[58]  M. Ratner,et al.  Aspects of Intervalence Charge Transfer in Cyanide-Bridged Systems: Modulated Electric Field Assessment of Distances, Polarizability Changes, and Anticipated First Hyperpolarizability Characteristics , 1998 .

[59]  Z. Otwinowski,et al.  [20] Processing of X-ray diffraction data collected in oscillation mode. , 1997, Methods in enzymology.

[60]  J. Oudar,et al.  Hyperpolarizabilities of the nitroanilines and their relations to the excited state dipole moment , 1977 .

[61]  Yusuke Mori,et al.  Growth of high quality nonlinear optical crystal 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) , 1999 .

[62]  Peter Günter,et al.  Electro‐optic properties of the organic salt 4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium tosylate , 1996 .

[63]  Mark A. Ratner,et al.  Chromophoric Self-Assembled Multilayers. Organic Superlattice Approaches to Thin-Film Nonlinear Optical Materials , 1990 .

[64]  S. Gorjian,et al.  The Synthesis of Some Lipophilic Tetradentate Ligands for Use in the Formation of Metal-Linked Polymers , 1994 .