Modeling of configurations and third-order nonlinear optical properties of methyl silsesquioxanes

Configuration optimizations, excited state properties, and the frequency-dependent third-order nonlinear optical polarizabilities have been investigated on a series of methyl-silsesquioxane (MeT) cages [CH(3)SiO(1.5)](n) (n=4, 6, 8, and 10) using ab initio quantum mechanical methods coupled with the sum-over-states methods. The obtained electronic absorption spectra show a redshift as the cage size increases, and the absorption spectra are assigned as charge transfers from oxygen p type to silicon s type atomic orbitals. The calculated average third-order polarizabilities of in the three optical physical processes (third-harmonic generation, the electric-field-induced second-harmonic generation, and degenerate four-wave mixing) have wide nonresonance regions. For all the considered species, the values of gamma decrease in the order of [MeT](4)>[MeT](8)(C(2v))=[MeT](10)>[MeT](6)>[MeT](8)(O(h)).     

Calculations on nonlinear second-order optical susceptibility of substituted fullerenes C 59X(X = B,N)

The second-order nonlinear susceptibility β of substituted fullerenes C ₅₉ X (X = B, N) is calculated by using the Su-Schrieffer-Heeger (SSH) model and the sumover-states (SOS) method. Obtained results indicate that the substituted doped balls C ₅₉ X have larger β values than C ₆₀/N, N-dicthylaniline and pure C ₆₀. The large second-order nonlinearities of C ₅₉ X stems from the large change in dipole moment accompanied by intramolecule charge transfer transitions and the relatively low-lying charge transfer excitation energies.     

Theoretical study on a novel series of fullerene-containing organometallics Fe(eta5-C55X5)2 (X = CH, N, B) and their large third-order nonlinear optical properties

Geometry structures, electronic spectra, and third-order nonlinear optical (NLO) properties of Fe(eta (5)-C 55X 5) 2 (X = CH, N, B) have first been investigated by time-dependent density functional theory. We analyzed the intramolecular interactions between ferrocene and the C 50 moiety. The calculated electronic absorption spectrum indicates that the short wavelength transitions are ascribed to the C 50 moiety mixed charge transfer transition of ferrocene itself, while the low energy excitation transitions are ascribed to the unique charge transfer transition from ferrocene to C 50 moiety in these systems. The third-order polarizability gamma values based on sum of states (SOS) method show that this class of ferrocene/fullerene hybrid molecule possesses a remarkably large third-order NLO response, especially for Fe(eta (5)-C 55B 5) 2 with the static third-order polarizability (gamma av) computed to be -10410 x 10 (-36) esu and the intrinsic second hypepolarizability to be 0.250. Thus, these complexes have the potential to be used for excellent third-order nonlinear optical materials. Analysis of the major contributions to the gamma av value suggest that the charge transfer from ferrocene to C 50 moiety along the z-axis (through Fe atom and the centers of two hybrid fullerenes) play the key role in the NLO response. Furthermore, boron substitution is an effective way of enhancing the optical nonlinearity compared to CH and N substitution, owing to smaller energy gap and better conjugation through the whole molecule.     

Electronic and Magnetic Structures of New Interstitial Boron Sub-Oxides B12O2:X (X = B,C, N,O)

The boron-rich boron sub-oxide rhombohedral B₆O considered in B₁₂O₂ full formulation has a large O-O spacing of ~3 Å and a central vacant position that can receive interstitial atoms X, forming a central O-X-O alignment in the dodecaboron cage as observed in well-known triatomic B₁₂ compounds as B₁₂{C-C-C}, B₁₂{N-B-N}, etc. Plane wave density functional theory (DFT) based calculations of unrestricted geometry relaxation of B₁₂{O-X-O}, X = B, C, N, and O let one identify new ternary sub-oxides, all found cohesive while showing different d(X-O) distances ranging from d(B-O) = 1.95 Å down to d(O-O) = 1.73 Å with intermediate d(C-O) = 1.88 Å. The different magnitudes were assigned to the chemical affinities of X-inserts versus host oxygen with the increasing development of X-O bonding along the series with larger cohesive B₁₂{O-O-O}. From the atom projected charge density, B presents none, while significant magnitudes are shown on C and N, the latter developing bonding with terminal oxygen atoms especially N. The presence of unpaired valence electrons leaves nonbonding charge density on X = C, N interstitial compounds, which, besides the relative isolation of the central C and N lead to the onset of magnetic moments: M(C) = 1.9 μ_B, and M(N) = 1 μ_B in a ferromagnetic ground state. Atom-resolved assessments are provided with the magnetic charge density and electron localization function electron localization function (ELF) projections on one hand and the site and spin projected density of states and the chemical bonding based on the overlap integral S_ij within the COOP criterion, on the other hand.     

呋喃同系物C4H4X(X=O,S,Se,Te)三阶非线性光学性质的理论方法比较研究

用ab initio HF，MP2和DFT三种方法的计算结果，根据完全态求和公式自编程序计算了呋喃同系物的三阶非线性光学极化率．结果表明随着杂原子序数的增大，体系的三阶非线性极化率也随着增大，从对称性出发，利用二态模型讨论了体系光学非线性增大的原因．     

One-pot synthesis and third-order nonlinear optical properties of AgInS2 nanocrystals

Good quality colloidal nanocrystals of metastable orthorhombic phase of AgInS2 obtained by decomposing the single-precursor [(Ph3P)2AgIn(SCOPh)4] in a mixture of dodecanethiol and oleic acid at 125-200 degrees C, exhibit significant third order non-linear optical properties.     

(M4H3X)2B2O2: hydrometal complexes (M = Ni, Mg) containing double tetracoordinate planar nonmetal centers (X = C, N)

Geometrical optimizations and electronic structural analyses of the -O(2)B(2)- bridged hydrometal complexes (M(4)H(3)C)(2)B(2)O(2) and (M(4)H(3)N)(2)B(2)O(2)(2+) (M = Ni, Mg) containing double tetracoordinate planar nonmetals (TPN) have been performed using the density functional theory at the B3LYP/6-311+G(d,p) level. Theoretical evidence of the possibility of double TPN centers coexisting in one planar molecule is presented.     

Heterometallic copper(Ⅱ) vanadates: synthesis,crystal structures and third-order nonlinear optical properties

Three polymeric heterometallic clusters with 1D, 2D, and 3D frameworks, constructed from a cyclic vanadate {V4O12}4-building block and three geometric constraint ligands, were synthesized by a one-pot self-assembly reaction. Z-scan experiments demonstrated that all the three cluster polymers have large hyperpolarizability γ values. TD-DFT calculations afforded insight into the electronic transitions and spectral characterization of these novel NLO molecular materials.     

C36X(X=O,NH,S)各种可能异构体的芳香性研究

采用拓扑共振能方法对富勒烯C36X(X=O,NH,S)开环结构中的所有可能的异构体及阳离子和阴离子芳香性进行了理论研究. 计算结果表明,C36X的芳香性高于C36. C36X的阳离子因其共振能为负值而具有反芳香性. 反之,C36X的阴离子因共振能为正值而具有芳香性和较高的稳定性. C36的D6h和D2d异构体中杂原子X插入在5-5键时得到的化合物最稳定. 从理论上预测了C36X的负离子能形成稳定的金属富勒烯. 对C36X的阳离子和阴离子的芳香性进行了解释.     

C59XH（X=N,B）与1,3-丁二烯Diels-Alder环加成反应的区域选择性

应用半经验的AMI和密度泛函B3LYP/6-31G*方法对1,3-丁二烯与C59XH(X=N,B)Diels-Alder环加成反应的区域选择性进行理论研究,选择一些有代表性的C59XH(X=N,B)的6-16键探讨环加成反应的机理.1,3-丁二烯与C59NH进行的Diels-Alder反应,随着加成位置远离C59NH的N原子,活化能越来越低,但都比1,3-丁二烯与C60相应反应的活化能高.与此相反,对于1,3-丁二烯与C59BH进行的环加成反应.加成位置最靠近B原子的2,12/r-和2,12/f-过渡态的势垒最低,并且比1,3-丁二烯与C60进行环加成反应的活化能约低18 kJ·mol-1,其产物也是热力学最稳定的.与C60相应的反应相比,C59NH和C59BH中N和B原子不同的电子性质对其邻位双键进行Diels-Alder环加成反应的活性产生了不同影响,前者使反应活性降低,后者使反应活性增强.     

Rational synthesis, structural characterization and the third-order nonlinear optical properties of two new M-Cu-S (M = Mo or W) clusters

By the additional reaction of binuclear compounds (Me4N)2M2S4 (TDT)2 (M = Mo, W; H2TDT= H2CH3C6H3S2) with mononuclear cuprous complex, two new M-Cu-S clusters Mo2Cu2S4(TDT)2-(PPh3 )2·CH3CH2OH (1) and W2Cu2S4(TDT)2(PPh3)2·0.5CH3CH2OH-0.5H2O (2) have been prepared and characterized by IR, UV-Vis, 31P NMR spectroscopy, cyclic voltammetry and single crystal X-ray structure analysis . Both compounds crystallize in space group P 21 / n with lattice parameters a = 1.0956(3), b = 2.2072(3), c = 2.4340(3) nm, β= 100.36(2)°, V= 5.790(3) nm3 and Z = 4 for 1 and a = 1.0965(9),b= 2.2135(3), c = 2.4317(4) nm, β = 99.63(8)°, V= 5.819(8) nm3 and Z = 4 for 2. Both molecular structures contain a cubane-like cluster core [M2Cu2S4] (M = Mo, W) and their skeletons are almost the same except for M atoms. The syntheses, structures and spectrum characterizations of these two clusters are discussed. The third-order nonlinear optical (NLO) property of the two clusters was studied by the technique of forward degenerate four     

Dispersion of the third-order nonlinear optical properties of an organometallic dendrimer(1)

The dispersion of cubic nonlinearity in the organometallic dendrimer 1,3,5-(3,5-{trans-[(dppe)2(4-O2NC6H4CC)RuCC]}2C6H3CCC6H4-4-CC)3C6H3 can be understood in terms of an interplay of two-photon absorption and absorption saturation. Simple dispersion relations reproduce the behavior of both the real and imaginary components of the hyperpolarizability.     

A series of metal-organic polymers assembled from MCl2 (M = Zn, Cd, Co, Cu): structures, third-order nonlinear optical and fluorescent properties

In this paper four metal-organic polymers {[Zn(fcz)Cl2].CH3OH}n 1, {[Cd(fcz)2Cl2].CH3OH.2H2O}n 2, {[Co(fcz)2Cl2].2CH3OH}n 3 and {[Cu(fcz)2Cl2].2CH3OH}n 4 (fcz = fluconazole: alpha-(2,4-difluorophenyl)-alpha-(1H-1,2,4-triazol-l-ylmethyl)-1H-1,2,4-triazole-l-ethanol) were synthesized and characterized by X-ray single crystal diffraction. Polymer consists of 1-D infinite chains arranged along the b-axis. All of polymers 2-4 exhibit a 2-D rhombohedral grid structure. We study the third-order nonlinear optical properties of fcz and polymers 1-4 in DMF solution by using 8 ns laser pulses at 532 nm, and find that 1 and 4 exhibit different NLO properties from fcz and both 2 and 3 show similar NLO properties to fcz. 1 possesses strong NLO refractive effects and large NLO absorptive behaviors. 2, 3 and fcz exhibit strong refractive effects, but their NLO absorptive behaviors are weaker than that of 1. The NLO effects of 4 are very weak. The study of optical limiting (OL) effects by using 40 ps laser pulses at 532 nm shows that fcz and polymer 3 possess a strong OL effect. The optical limiting threshold values of 0.15 J cm(-2) for fcz and 0.16 J cm(-2) for are comparable to those of many heterothiometallate clusters. Polymers 1, 2 and 4 show a weak OL effect. The fluorescent spectra in DMF solution (concentration: 1 x 10(-4) mol dm(-3)) show that polymers 1-4 exhibit different luminescence properties from fcz. The maximum wavelength of polymers 1-3 are blue shifted gradually by 2-12 nm while polymer 4 exhibits a fluorescent self-quenching phenomenon. These results demonstrate that metal ions play an important part in the NLO and fluorescent properties of coordination polymers.     

Synthesis,crystal structure,and third-order nonlinear optical properties of a copper(I) one-dimensional coordination polymer

A copper(I) thiocyanate coordination polymer [Cu(Phen)(μ-NCS)]n (I) (Phen = 1,10-phenan-throline) has been synthesized by the low-temperature solid-state reaction. Single-crystal X-ray analyses reveal that compound I possesses a type of one-dimensional (1D) framework structure. Polymer I was characterized by elemental analyses, IR spectra, and UV-visifele spectra. The third-order nonlinear optical properties were also investigated, and they exhibit good nonlinear absorption and self-defocusing performance with modulus of the hyperpolarizability 4.94 × 10⁻³⁰ esu for I in a 6.35 × 10⁻⁴ mol dm⁻³ DMF solution.     

Heteroatom effects on allenic seven-membered ring X2C4H4C (X = CH,N, P,and As)

Stable configurations of seven-membered rings X₂C₄H₄C (1 _X , X = CH, N, P, and As) in the singlet (s) and triplet (t) states are found at B3LYB/6-311++G** level of theory. Thermal energy gaps, ΔE _s-t; enthalpy gaps, ΔH _s-t; Gibbs free energy gaps, ΔG _s-t, between the singlet and triplet states of 1 _X were estimated at the same level of theory. The ΔG _s-t gap between the singlet and triplet states of 1 _X changes in the order: 1 _P > 1 _As > 1 _N , respectively.     

酞菁和酞菁铜的三阶非线性光学性质

用INDO/SDCI方法研究了酞菁和酞菁铜的电子结构, 紫外-可见光谱, 三阶非线性光学系数及其色散效应, 发现酞菁铜中Cu^2+对γ的贡献很小, 故酞菁与酞菁铜的γ几乎相等, 我们的计算结果对此进行了合理的解释。     

(N,N, N′, N′-tetramethylethylenediammonium)Cu2X6 (X=Cl,Br): crystal structure and magnetic interactions

Summary The crystal structures of (Me₄enH₂)Cu₂Cl₆ and (Me₄enH₂)Cu₂Br₆ have been determined. The triclinic crystals contain chains of symmetrically bibridged [Cu₂X₆]^2– dimers. Within the dimers the Cu–X distances average 2.299 Å (Cl) and 2.408 Å (Br) and the Cu–X–Cu angles are 96.4(1)^o (Cl) and 95.7(1)^o (Br). Longer Cu–X bonds, 2.679(1)Å (Cl) and 2.761(3)Å (Br), link dimers together into infinite chains via asymmetrical bridges. The bridging angles for the asymmetric bridge are 92.2(1)^o (Cl) and 89.4(1)^o (Br). Magnetic susceptibility data for both compounds are indicative of antiferromagnetic coupling. Analyses of the data yields J/k=–23(1)K (Cl) and –82(2)K (Br) for the interdimer coupling and J/k=–5(1)K (Cl) and –4(1)K (Br). The intradimer coupling for the chloride is in accord with magneto-structure relations deduced for similar salts. Similarly, the increased antiferromagnetic contribution upon substitution of Cl by Br follows trends previously observed.