Fullerenes, nonlinear optical properties

E. Westin, Calculations of Linear and Nonlinear Optical Properties of Ionic Crystal Surfaces and Fullerenes Thesis Chalmers University of Technology, Goteborg, 1995. 

Shuai, Z., Bredas, J.L. Electronic structure and nonlinear optical properties of fullerenes C q and C70 A valence-effective-Hamiltonian study. Phys. Rev. B 46, 16135-16141 (1992)... 

It is not possible to give here a complete review of DMol applications, so only a non-systematic selection of applications is mentioned here. Applications to chemical reactions have been studied by Seminario, Grodzicki and Politzer [10]. Buckminster-fullerenes have been studied by various groups [11] including also nonlinear optical properties [8] and the geometrical structure of Cs4 [13]. Cluster model studies of surfaces with adsorbates are reported in [14-17]. Cluster models for point defects in solids, in particular spin density studies of interstitial muon can be found in [18,19]. Spin density studies of molecular magnetic materials are in ref [20]. Polymers have been studied by Ye et al [21]. 

The synthesis of fullerene-containing polymers is noteworthy for several reasons. On the one hand, once Cgg is attached to a polymer, most of the fullerene properties are transferred to the polymer. Thus, for instance, electroactive and photoactive polymers or polymers with nonlinear optical properties can be prepared. On the other hand, hardly processible fullerenes embedded in highly soluble polymers may become more easily amenable to further treatments. The resulting materials might eventually be used for surface coating, photoconducting devices, or to create new molecular networks. 

Linear and Nonlinear Optical Properties of Fullerene Derivatives and Endohedral Fullerenes... 

Loboda O, Zaleshy R, Avramopoulos A, Luis J-M, Kittman B, Tagmatarchis N, Reis H, Papadopouls MG (2009) Linear and nonlinear optical properties of [60] fullerene derivatives. J Phys Chem A 113 1159-1170... 

Mateo-Alonso, A., Iliopoulos, K., Couris, S. and Prato, M. Efficient modulation of the third order nonlinear optical properties of fullerene derivatives. J. Am. Chem. Soc. 130,1534—1535, 2008. 

Two main aspects of the present contribution can be generalized and formulated as follows. Firstly, we compute both electronic (Sect. 3.2.2) and vibrational (Sect. 3.2.4) contributions to (hyper)polarizability. Thus, we explore the limitations of the currently available computational procedures. Secondly, we associate the linear and nonlinear optical properties of investigated organofullerenes with their electronic structure (Sect. 3.2.3). The purpose of the analysis of the relations between NLO properties and structure of organofullerenes is to make a basis for further rational design of new [60]fullerene derivatives suitable for photonic applications. 

The structure(Zn,Ph)-property(a,/ ,7,) relationship has been investigated in this work by semiempirical PM3 and PM6 methods. The ZnTPP-(C)4-[60] dyad was found to exhibit large values of second hyperpolarizability. We found almost linear correlation between the size of the conjugated polyalkynyl linkage and the optical properties of the whole fullerene-porphyrin dyad. As a part of the present study, we have found that the nonlinear optical properties of model donor-substimted [60]fullerene derivatives are poorly described by the BLYP functional. The long-range corrected LC-BLYP functional, on the other hand, successfully cures the overshoot problem both for / and 7. The calculations for A-methylfulleropyrrolidine shows that the linear absorption spectra is reproduced quite well by conventional PBEO and B3LYP functionals. 

The first chemical transformations carried out with Cjq were reductions. After the pronounced electrophilicity of the fullerenes was recognized, electron transfer reactions with electropositive metals, organometallic compounds, strong organic donor molecules as well as electrochemical and photochemical reductions have been used to prepare fulleride salts respectively fulleride anions. Functionalized fulleride anions and salts have been mostly prepared by reactions with carbanions or by removing the proton from hydrofullerenes. Some of these systems, either functionalized or derived from pristine Cjq, exhibit extraordinary solid-state properties such as superconductivity and molecular ferromagnetism. Fullerides are promising candidates for nonlinear optical materials and may be used for enhanced photoluminescence material. 

The reaction is conducted the same way as with MWNT with the sole difference of employing toluene instead of DMF as a solvent. This is because the nanotubes present as impurity in the sample are insoluble in toluene, whereas in DMF, they would be dispersed too, and participate in the reaction with the azomethine yiides. In toluene, on the other hand, only fullerenes and onions are sufficiently dispersed. The obtained samples feature interesting nonlinear optics (NLO) properties. In the meantime, one has also succeeded in generating on the onions surface carboxyl groups subsequently to be functionalized by reaction with amines (Figure 4.40). 

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