新型双重电荷转移分子的二阶非线性光学性质的 理论研究

以INDO/SCI方法为基础,按完全态求和(SOS)公式编制了计算分子二阶非线性光学系数β~i~j~k和β~μ的程序。研究了1,2-二氨基-4,5-二硝基苯1和其异构体1,3-二氨基-4,6-二硝基苯2的电子光谱和二阶非线性光学性质。计算表明分子1具有与分子2几乎相等的二阶非线性极化率。但由于分子1的偶极矩明显大于分子2的,故分子1的μβ值比分子2的μβ值大的多。在此基础上,研究了2,3-二(β-苯乙烯基)-5,6-二氰基吡嗪和2,3-二(β-噻吩乙烯基)-5,6-二氰基吡嗪和2,3-二(β-噻吩乙烯基)-5,6二氰基吡嗪衍生物的电子光谱和二阶非线性光学性质。结果表明,这些化合物均具有两个相距很近的强吸收峰,它们对β值的呈加和模式。由于这类化合物特征吸收峰均位于413nm以下且具有大的μβ值,所以,它们是一类很有前途的二阶非线性光学候选材料。     

Synthesis and characterization of new thienylpyrrolyl-benzothiazoles as efficient and thermally stable nonlinear optical chromophores

The synthesis and full characterization of new chromophores with second-order nonlinearities containing thienylpyrrolyl and benzothiazolyl moieties are reported. The solvatochromic behavior of the compounds was investigated. The hyperpolarizabilities β of derivatives 4-6 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that strong nonlinearity is balanced by good thermal stability especially for chromophores 6b and 6c, making them good candidates for NLO applications.     

Preparation of polymer optical fibers doped with nonlinear optical active organic chromophores

We synthesized two novel organic nonlinear optical chromophores—chiral S(+)‐N‐[p‐(4‐nitrostyryl) phenyl] prolinol and non‐chiral [p‐(4‐nitrostyryl) phenyl] piperdine—as potential laser‐active dyes for photonic applications. Both materials show good optical transmittance in the telecommunication frequency region, desirable solubility in acrylic polymer optical fiber matrices, and attractive fluorescence properties that are advantageous for laser‐gain materials and devices. Subsequently, these two chromophores were incorporated into poly(methyl methacrylate) and poly(ethyl methacrylate) and drawn into polymer optical fibers. The relevant properties of these organic dye‐doped fibers have been studied, revealing essential attributes of laser‐active characteristics. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1794–1801, 2001     

Synthesis, nonlinear optical properties and the possible mechanism of photopolymerization of two new two-photon absorption chromophores

Efficient Witting and Pd-catalyzed Heck coupling methodologies are employed to synthesize two new two-photon free-radical photopolymerization initiators 9-ethyl-3-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-9H-carbazole (abbreviated to EPVPC) and 9-octadecyl-3-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-9H-carbazole (abbreviated to OPVPC). The experimental results confirm that the two compounds are good two-photon absorbing chromophores and operative two-photon photopolymerization initiators. The calculated two-photon absorption cross-sections of EPVPC and OPVPC are 56.6 and 62.0×10⁻⁵⁰ cm⁴ s photon⁻¹, respectively. A microstructure by using EPVPC as initiator has been fabricated under irradiation of 200 fs, 76 MHz Ti:sapphire femtosecond laser at 780 nm. The possible mechanism of photopolymerization is discussed.     

Synthesis and nonlinear optical properties of copolymers of fluoro-containing bisphenol A and chromophores

A series of new fluoro-containing copolymers have been synthesized by a Mitsunobu reaction with 4,4’-（hexafluoroisopropylidene） bisphenol A（6FBPA） and the corresponding N,N-dihydroxyethylaminoaryl azo or ring-locked triene compounds, which have high thermal stability and good solubility in organic solvents.The nonlinear optical（NLO） measurements made by Marker fringe method at 1064 nm indicate that the copolymers embedded with the ring-locked triene and azo chromophores exhibit higher macroscopic nonlinear optical coefficient（70.2 pm/V and 26.5-34.6 pm/V,respectively）.Thermal analysis and UV-visible absorption spectra show that the copolymers have good thermal stability（T_d= 264-319℃） and optical transparency (λ_max<500 nm).     

Nonlinear optical properties of novel H-shaped chromophores

Novel and effective H-shaped chromophores were doped into polymethyl methacrylate (PMMA) to form guest-host polymer thin films.The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a guest exhibit high second harmonic coefficients (d33) compared with other two-dimensional chromophores.     

Theoretical study on the second‐order nonlinear optical properties of nonconjugated D‐π‐A chromophores

Density functional theory calculations have been carried out on nonconjugated D‐π‐A chromophores to investigate the different electron donors and conjugated bridges effects on the molecular nonlinear optical response. The results show that the large second‐order polarizability values can be achieved through careful combination of available electron donors, conjugated bridges for our studied nonconjugated D‐π‐A chromophores. The calculations also provide a clear explanation for the second‐order polarizability changes from the standpoint of transition energies, oscillator strengths, electron density difference, and bond length alternation. Solvent effect has great influence on the second‐order polarizability and electronic absorption spectrum. It is hoped that the results presented in this article will give some hints to the interrelated studies. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Nonlinear optical properties of some side chain copolymers based on benzoxazole containing chromophores

Acrylate‐methylmethacrylate copolymers have been synthesized for nonlinear optical applications. Acrylate monomer units are characterized by the presence in the side chain of phenylbenzoxazole groups containing electron donor‐electron acceptor substituents. The phase behavior of all polymers has been investigated by DSC, X‐ray diffraction and polarizing microscopy: two of them exhibit liquid crystalline behavior of smectic type. For four polymers, nonlinear optical properties have been examined by second harmonic generation measurements on thin films (∼ 1 μm thickness) electrically poled by corona discharge. Second order susceptibility coefficients d₃₃ and average relaxation times 〈τ〉, relative to the time stability of the chromophore poling, have been measured. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 603–608, 1999     

Molecular structure and nonlinear optical properties of a tetrasilver(I) phosphonitocavitand

A tetrasilver(I) phosphonitocavitand was synthesized and structurally characterized. The compound crystallizes in the monoclinic space group P2₁/n with a=15.0151(13), b=39.832(4), c=15.2479(14) Å, β=95.1000(2)°, V=9083.3(14) Å³ and Z=4. The structure contains four coplanar silver atoms bridged by four μ-Cl and one central trapped μ₄-Cl atoms in the inside of the closing bowl-shaped cavitand. Nonlinear optical properties of this metal-cavitand were investigated. Optical limiting effect with threshold of 0.6 J cm⁻² was observed with the laser pulses of 7 ns at 532 nm.     

Second and third-order nonlinear optical properties and molecular parameters of azo chromophores: semiempirical analysis

The static and frequency dependent average polarizability (〈α〉), first- and second-hyperpolarizabilities (〈β〉 and 〈γ〉) and highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) energies of nonlinear optical chromophores with nitro acceptors 1–5 have been investigated by using the Austin Model 1 (AM1), Modified Neglect of Diatomic Overlap (MNDO), MNDO with d orbitals (MNDO-d), Parameterization Method 3 (PM3), Recife Model 1 (RM1) and Parameterization Method 6 (PM6) methods within a time-dependent Hartree–Fock (TDHF) approaches. The electronic properties of chromophores 1–5 have been reported by employing two-state model calculated at Zerner's spectroscopic version of the Intermediate Neglect of Differential Overlap singly excited configuration interaction (ZINDO/S-SCI) method. Also, the molecular hardness (η) and electronegativity (χ) parameters have been obtained by using molecular frontier orbital energies. The 〈α〉, 〈β〉, 〈γ〉 HOMO, LUMO energies, η and χ parameters have been investigated with respect to the choice of different semiempirical methods.     

N-取代螺旋共轭化合物非线性光学性质的理论研究

以量子化学半经验AM1方法优化几何构型为基础，采用FF／AMl和INDO-SOS方法计算了N-取代螺旋共轭化合物的非线性光学系数，讨论了N原子不同取代位置对螺旋共轭体系结构、电子光谱、非线性光学系数的影响．计算结果表明，N杂原子的引入可改善体系的非线性光学性质，所设计的分子具有较大的二阶非线性光学系数和较好的透明性．     

不对称-NO等取代2,4-二苯基方酸的非线性光学性质的FF/AM1研究

对-NH2,-NO和NO2取代的2,4-二苯基方酸采用量子化学半经验AM1方法进行优化,在优化稳定构型的基础上计算了各体系的电子光谱,并通过FF/AM1方法计算了各体系的一阶分子超极化率(β ijk)和二阶分子超极化率(γ ijkl).计算结果表明,各体系均有非常大的βijk和γijkl,其最大值分别可达-2.406×10-26 C*m和1.845×10-24 C*m.     

Evaluation of the thermal stability of some nonlinear optical chromophores

Optical data storage is poised to benefit from a new class of advanced polymeric materials engineered to exhibit photorefractivity. Likewise, the transmission and processing of data will also benefit from a related class of materials with electro-optic activity. Organic chromophores are critical constituents of these materials which function due to a change of index of refraction in response to an electric field. However, a number of materials and processing problems remain to be solved before devices incorporating these optically nonlinear chromophores are practical. For example, for electrooptical applications the NLO waveguide should be able to withstand short duration processing temperatures in excess of 300°C and long duration use temperatures of at least 80°C. The requirement for thermochemical stability follows from the need to implement highT _g matrices to provide stability of the orientational or polar order required for long-term device performance and reliability. As a result, the thermal stability of chromophores is now more closely evaluated in addition to their transparency and optical nonlinearity properties. Some chromophore classes, such as the azo dyes studied here, have attractive properties for these applications but further enhancements in overall properties are needed. Identification of the fundamental chemical processes in thermal decomposition of these dyes should lead to introduction of structural changes which provide better stability. Here thermogravimetric analysis (TGA) coupled with mass spectrometry (TGA/MS) is used to provide an assay of thermochemical stability with an added benefit that insight into the mechanisms of thermal decomposition may by identified. In this initial study diaryl substitution of the amine in derivatives of 4-amino-4-nitroazobenzene was observed to greatly enhance thermal stability relative to dialkyl substitution. Substitution of phenyl for alkyl eliminates structural features involved in the most facile degradation mechanism available to the alkyl derivative.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayThe authors acknowledge contributions by colleagues at IBM including H. Truong and R. Siemens for the thermal analysis. This work was supported by the Air Force Office of Scientific Research and the National Institute of Science and Technology Advanced Technology Program.     

Theoretical investigation on second-order nonlinear optical properties of (dicyanomethylene)-pyran derivatives

On the basis of the ZINDO program, we have designed a program to calculate the second-order nonlinear polarizabilities β_ijk, β₀ and β_μ according to the sum-over-states (SOS) expression. A series of new 4-(dicyanomethylene)-2-methyl-6-(p-dithylamino-styryl)-4H-pyran (DCM) derivatives were designed and their electron spectra and nonlinear optical properties were studied. It is proposed that these compounds possess two important excited states close to each other in energy, both contributing to hyperpolarizability in an additive fashion; 4-(dicyanomethylene)-2,6-bis-(p-donor-styryl)-4H-pyran derivatives are more nonlinear than 4-(dicyanomethylene)-2,6-bis-(p-donor-phenyl)-azo-4H-pyran derivatives. The high nonlinearities, good thermal stability and high transparency make them attractive candidates for second-order nonlinear applications such as electro-optic modulators and frequency doublers.     

Synthesis and second-order nonlinear optical properties of new chromophores containing benzimidazole, thiophene, and pyrrole heterocycles

A new series of thermally stable benzimidazole-based nonlinear optical (NLO) chromophores 4 and 5 have been developed. These chromophores possess a thienylpyrrolyl π-conjugated system attached to functionalized benzimidazole heterocycles. This feature leads to robust chromophores with excellent solvatochromic properties, high thermal stabilities and good molecular optical nonlinearities.     

Synthesis and nonlinear optical properties of new symmetrically substituted stilbenes

Three new chromophores and trans-4-(N-(ethyl 4″-nitrobenzoate)-N-ethyl amino)-4′-(dimethyl amino) stilbene (DMANHAS) have been synthesized and whose chemical structures have been characterized by ¹H NMR, IR, and elemental analyses. Linear absorption, single-photon-induced fluorescence and two-photon-induced fluorescence are experimentally studied. Trans-4-(N-2-hydroxyethyl-N-ethyl amino)-4′-(dimethyl amino)stilbene (DMAHAS) and trans-4-(N-2-hydroxyethyl-N-ethyl amino)-4′-(diethyl amino)stilbene (DEAHAS) have effective two-photon absorption cross-sections of σ₂=0.91×10⁻⁴⁶ cm⁴ s/photon and σ₂=1.19×10⁻⁴⁶ cm⁴ s/photon at 532 nm by using an open aperture Z-scan technique, respectively. When pumped with 800 nm laser irradiation, DMAHAS and DEAHAS indicate strong two-photon-induced blue fluorescence of 436 and 440 nm, respectively, while trans-4-(N-(ethyl 4″-nitrobenzoate)-N-ethyl amino)-4′-(diethyl amino) stilbene (DEANHAS) and DMANHAS exhibit no fluorescence.     

苯并噻二嗪衍生物电子结构和非线性光学性质的研究

运用量子化学PM3方法，对苯并噻二嗪几种衍生物的几何构型、电子结构和前线分子轨道成分进行了分析，研究了电荷分布规律。同时，基于体系中电子转移的特点，利用有限场FF方法探讨了其非线性光学性质的变化。结果表明，苯并噻二嗪分子具有较好的二阶非线性光学性质，并可能成为一类良好的光学材料。     

Synthesis,structure and nonlinear optical properties of two novel two-photon absorption chromophores

Two triphenylamine-based derivatives that can be used as two-photon absorption chromophore,tris{4-[4-(3-trifluoromethyl-3-oxopanoyl)]phenyl}amine (1) and tris{4-[4-(3-phenyl-3-oxopanoyl)] phenyl} amine (2) were successfully synthesized and fully characterized by elemental analysis,IR,1H NMR and MS. The single crystal X-ray diffraction analysis showed that the molecules possess D-(π-A)3 structures. One-and two-photon absorption and fluorescence in various solvents were experimentally investigated. A data rec...     

New 4,4-oligophenylenevinylene functionalized-[2,2]-bipyridyl chromophores: synthesis, optical and thermal properties

The synthesis and characterization of new bipyridyl-based chromophores featuring extended oligophenylenevinylene π-conjugated backbones are reported. Their absorption and emission properties as well as their thermal stabilities are discussed in comparison to those of the parent ligand.