研究领域

Inorganic Chemistry Main Group Chemistry Supramolecular Chemistry Materials Chemistry

How far can we push chemical self-assembly? This is one of the current big questions� in science. Hydrogen bonds and the coordination of metal ions have been the most-commonly used forces to drive the spontaneous organization of small building blocks into large, complex, and sometimes functional structures. The use of pi-stacking and van der Waals forces is now well documented. Other intermolecular forces have not been used mostly because they have been poorly understood until now, as is the case for the inter-atomic contacts made by the heavy p-block elements. The succession of names given to this phenomenon parallels the evolution of our understanding: the initial 'non-bonded contact" became"weakly bonding interaction" and now the term "secondary bonding interaction"(SBI) is gaining increasing acceptance. Our research program pursues the use of SBIs of heavy p-block elements in supramolecular chemistry and molecular self-assembly. SBIs have distinctive features that can be exploited to control the properties of self-assembled materials. For example, while hydrogen bonds are barriers to electron mobility, SBIs enhance conductivity. In addition, SBIs can stabilize compounds with unusual compositions. In summary, new interactions translate in new properties. Noncentrosymmetric supramolecular structures exhibit nonlinear optical (NLO) properties, there are many known examples of supramolecular NLO materials built with hydrogen bonds. However, hydrogen bonds absorb light in the near-infrared and such materials are not useful in optical fibre technology. SBIs vibrate at much lower frequencies and their supramolecular nonlinear optical materials should have greater transparency. An additional advantage to using heavy elements, the soft electron clouds of these atoms result in unusually strong nonlinear properties. This is precisely a second major interest of our group. We have designed and synthesized molecules with promising nonlinear activity and have developed our own Second Harmonic Generation spectrometer with a tunable excitation wavelength.

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L. M. Lee, I. Vargas-Baca, "Oxygen, sulfur, selenium, tellurium and polonium", Annu. Rep. Prog. Chem., Sect. A, 2012, DOI: 10.1039/c2ic90019j. Invited review. A. Nordheider, T. Chivers,* R. Thirumoorthi, I. Vargas-Baca, J. D. Woollins, "Planar P6E6 (E = Se, S) Macrocycles Incorporating P2N2 Scaffolds", Chem. Commun. 2012, 48, 6346 - 6348. R. Thirumoorthi, T. Chivers,* I. Vargas-Baca,* "Experimental and Theoretical Investigations of Tellurium(IV) Methanediides and Their Insertion Products with Sulfur and Iodine", Organometallics 2012, 31, 627-636. DOI: 10.1021/om200925k. K. V. Vasudevan, M. Findlater, I. Vargas-Baca, A. H. Cowley,* "Tetrakis(imino)pyracene Complexes Exhibiting Multielectron Redox Processes", J. Am. Chem. Soc. 2012, 134, 176-178. R. Thirumoorthi, T. Chivers,* I. Vargas-Baca,* "S,C,S-Pnictogen bonding in pincer complexes of the methanediide [C(Ph2PS)2]2-", Dalton Transactions 2011, 40, 8086-8088. A. F. Cozzolino, P. J. W. Elder and I. Vargas-Baca,* “A Survey of Tellurium-Centered Secondary-Bonding Supramolecular Synthons”, Coord. Chem. Rev. invited review, 2011, 255, 1426–1438, DOI:10.1016/j.ccr.2010.12.015. A. F. Cozzolino and I. Vargas-Baca,* “Parameterization of a Force Field for Te-N Secondary Bonding Interactions and its Application in the Design of Supramolecular Structures Based on Heterocyclic Building Blocks”, Crystal Growth & Design, 2011, DOI:10.1021/cg100951y. A. F. Cozzolino, P. S. Whitfield and I. Vargas-Baca,* “Supramolecular chromotropism of the crystalline phases of 4,5,6,7-tetrafluorobenzo-2,1,3-telluradiazole”, J. Am. Chem. Soc., 2010, 132, 17265-17270. A. F. Cozzolino, Q. Yang and I. Vargas-Baca,* “Engineering second-order nonlinear optical activity by means of non-centrosymmetric distortion of the [Te-N]2 supramolecular synthon”, Crystal Growth & Design, 2010, 10, 4959–4964. J. Kübel, P. J. W. Elder, H. A. Jenkins and I. Vargas-Baca,* “Structure and Formation of the First (-O-Te-N-)4 Ring”, Dalton Transactions, 2010, 39, 11126-11128. L. M. Lee, P. J. W. Elder, A. F. Cozzolino, Q. Yang and I. Vargas-Baca,* “An experimental and computational investigation of the formation and structures of N-hydro and N,N’-dihydro-benzo-2,1,3-chalcogenadiazolium chlorides”, Main Group Chem. 2010, 9, 117-133. Invited paper for a special issue in honour of Alan H. Cowley. K. V. Vasudevan, I. Vargas-Baca, and A. H. Cowley,* “Naphthalene-Mediated Electronic Communication in Tetrakis-(imino)pyracene Complexes”, Angew. Chem. Int. Ed. 2009, 48, 8369-8371. A. F. Cozzolino, S. Hanhan, A. D. Bain, I. Vargas-Baca, “N-Triphenylboryl- and N, N’-bis(triphenylboryl)- benzo-2,1,3-telluradiazole”, Chem. Commun. 2009, 4043-4045. F. O. Ogini, Philip J. W. Elder, James F. Britten, and I. Vargas-Baca,* "An investigation of (C5H5)Fe(C5H4-C(OBF3)-CH3)", Can. J. Chem. 2009, 87, 1055-1062. Invited paper for a special issue in honour of Tom Ziegler. N. J. Hill, I. Vargas-Baca, A. H. Cowley,* "Recent developments in the coordination chemistry of bis(imino)acenaphthene (BIAN) ligands with s- and p-block elements", Dalton Transactions, 2009, 240 - 253. This review is highlighted on the front cover of the journal. I. Vargas-Baca,* M. Findlater, A. Powell, K. V. Vasudevan, A. H. Cowley,* "Boron di- and trications", Dalton Transactions, 2008, 6421 - 6426. Y. Wang, J. Fonseca-Campos, W.-g. L., C.-q. Xu,* I. Vargas-Baca, "Noise analysis of second-harmonic generation in undoped and MgO-doped periodically poled lithium niobate", Adv. Optoelectronics, 2008, AID428971. A. F. Cozzolino, N. E. Gruhn, D. L. Lichtenberger, I. Vargas-Baca,* "The valence electronic structure of benzo-2,1,3-chalcogenadiazoles studied by photoelectron spectroscopy and density functional theory", Inorg. Chem. 2008, 47, 6220-6226. F. O. Ogini, Y. Ortin, A. H. Mahmoudkhani, A. F. Cozzolino, M. J. McGlinchey, I. Vargas-Baca,* "An Investigation of the Formation of 1,3,5-Heterosubstituted Benzene Rings by Cyclo-Condensation of Acetyl-Substituted Organometallic Complexes", J. Organomet. Chem. 2008, 693, 1957-1967. J. Fonseca-Campos, Y. Wang, W. Liang, C.-Q. Xu and I. Vargas-Baca, "Comparison of photorefractive effects in undoped and MgO-doped PPLN", Proc. SPIE-Int. Soc. Opt. Eng., 2007, 6796, 679619/1-679619/8.