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Benzi C, Barone V, Tarroni R, Zannoni C. Order parameters of alpha,omega-diphenylpolyenes in a nematic liquid crystal from an integrated computational and 13C NMR spectroscopic approach. J Chem Phys 2006; 125:174904. [PMID: 17100476 DOI: 10.1063/1.2363994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The orientational order parameters and conformational behavior of five relatively large rodlike molecules, biphenyl, trans-stilbene, 1,3-diphenyl-butadiene, 1,3,5-diphenyl-hexatriene, and 1,3,5,7-diphenyl-octatetraene, dissolved in the thermotropic liquid crystal ZLI-1167, have been studied using an integrated approach combining (13)C NMR measurements and quantum mechanical computations of carbon chemical shift tensors. Besides biphenyl, the phenyl moiety of all structures has been found to have a high rotational mobility in the temperature range of the present experiments. The rank-two order parameter <P(2)> in the nematic phase is found to increase steadily from the shortest to the longest term of the series at any temperature within the nematic range. The molecular biaxiality order parameter <D(02) (2)> is found to be small and essentially constant with temperature, giving further support to the common assumption of effective uniaxiality for these probes.
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Affiliation(s)
- Caterina Benzi
- Dipartimento di Chimica, Università Federico II, Complesso Monte S. Angelo, Via Cintia, I-80126 Naples, Italy.
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Thomas SW, Long TM, Pate BD, Kline SR, Thomas EL, Swager TM. Perpendicular Organization of Macromolecules: Synthesis and Alignment Studies of a Soluble Poly(iptycene). J Am Chem Soc 2005; 127:17976-7. [PMID: 16366528 DOI: 10.1021/ja056241u] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe herein a polymeric material that prefers to align perpendicular to a stretch-aligned polymer host in the solid state. Poly(iptycene) poly-1 was synthesized from monomer 1 under hyperbaric techniques via a Diels-Alder polymerization. Polarized excitation spectra of the anthracene end groups in this material in a stretch-aligned, solution-cast poly(vinyl chloride) (PVC) film showed that the poly(iptycene) prefers to align normal (counter aspect ratio) to the stretching direction of the PVC. This is explained by a "threading" mechanism, whereby the PVC intercalates through the internal free volume presented by poly-1, similar to effects observed in small molecule iptycenes under similar conditions.
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Affiliation(s)
- Samuel W Thomas
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Benzi C, Cossi M, Barone V, Tarroni R, Zannoni C. A Combined Theoretical and Experimental Approach to Determining Order Parameters of Solutes in Liquid Crystals from 13C NMR Data. J Phys Chem B 2005; 109:2584-90. [PMID: 16851261 DOI: 10.1021/jp045908g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ordering properties of an anisotropic liquid crystal can be studied by recording 13C NMR spectra at different temperatures for a number of rigid solutes. The traditional difficulty in analyzing 13C data comes from the scarcity of experimental information about the carbon shielding tensors and from their limited transferability among different solutes. We show that these obstacles can be overcome by computing high-level ab initio shielding tensors, also including the solvent effects by the polarizable continuum model. The reliability of this combined approach is carefully verified, and the order parameters of several solutes are obtained by reanalyzing previously published spectra. The quality of the results is shown to be comparable to deuterium NMR without the need of isotopic substitution.
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Affiliation(s)
- Caterina Benzi
- Dipartimento di Chimica, Università Federico II, Complesso Monte S. Angelo, via Cintia, I-80126 Napoli, Italy
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Arcioni A, van Zandvoort MAMJ, Bartolini P, Torre R, Tarroni R, Righini R, Zannoni C. Effective Shape and Dynamics of Chlorophyll a in a Nematic Liquid Crystal. J Phys Chem B 1998. [DOI: 10.1021/jp9726504] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alberto Arcioni
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Marc A. M. J. van Zandvoort
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Paolo Bartolini
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Renato Torre
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Riccardo Tarroni
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Roberto Righini
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
| | - Claudio Zannoni
- Dipartimento di Chimica Fisica e Inorganica, Università degli Studi di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, LENS (European Laboratory for Non-linear Spectroscopy), Università, Largo E. Fermi 2, I-50125 Firenze, Italy, and Dipartimento di Chimica, Università, Via G. Capponi 9, I-50121 Firenze, Italy
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