1
|
Green MM, Peterson NC, Sato T, Teramoto A, Cook R, Lifson S. A helical polymer with a cooperative response to chiral information. Science 2010; 268:1860-6. [PMID: 17797527 DOI: 10.1126/science.268.5219.1860] [Citation(s) in RCA: 689] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Polyisocyanates, long studied as theoretical models for wormlike chains in dilute solution and liquid crystals, differ from their biological helical analogs in the absence of a pre-determined helical sense. These polymers have an unusual sensitivity to chiral effects that arises from a structure in which alternating right- and left-handed long helical blocks are separated by infrequent and mobile helical reversals. Statistical thermodynamic methods yield an exact description of the polymer and the cooperative nature of its chiral properties. Minute energies that favor one of the helical senses drive easily measurable conformational changes, even though such energies may be extremely difficult to calculate from structural theory. In addition, the chiral nature of the polymer can be used to test theoretical ideas concerned with cholesteric liquid crystals, one of which solves the problem of assigning the helical sense.
Collapse
|
2
|
Celebre G, Ionescu A. Orientational mechanisms in liquid crystalline systems. 1. A reaction field analytical description of the interaction between the electric quadrupole moment of a probe solute and the electric field gradient of a nematic solvent. J Phys Chem B 2010; 114:228-34. [PMID: 20017545 DOI: 10.1021/jp907310g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present paper, the fundamental problem of calculating the electric field gradient (EFG) experienced by a highly idealized solute, represented by a general point quadrupole immersed in an anisotropic uniaxial medium, has been tackled. Following a generalized reaction field approach (based upon the original ideas and the "mean-field philosophy" due to Kirkwood and Onsager) in the linear response approximation, a closed analytical expression of the EFG has been derived (to the best of our knowledge, for the first time). The obtained expression is particularly simple and elegant, also thanks to the oversimplifying approximation that the virtual cavity containing the solute is assumed to be perfectly spherical. This compact and manageable formula, obtained by a rigorous mathematical derivation (unlike other mean-field phenomenological models previously suggested in literature) can be useful to investigate and better understand a likely orientational mechanism, partly responsible for the ordering of small solutes dissolved in nematic mesophases, based on the interaction between the electric quadrupole of the solute and the electric field gradient of the anisotropic uniaxial medium (in the next paper of this issue, the formulation obtained in this work is widely tested on a variety of uniaxial and biaxial solutes dissolved in different nematic solvents).
Collapse
Affiliation(s)
- Giorgio Celebre
- Dipartimento di Chimica, Università della Calabria, v. P. Bucci, I-87036 Rende (CS), Italy.
| | | |
Collapse
|
3
|
Celebre G, Ionescu A. Orientational mechanisms in liquid crystalline systems. 2. The contribution to solute ordering from the reaction field interaction between the solute electric quadrupole moment and the solvent electric field gradient. J Phys Chem B 2010; 114:235-41. [PMID: 20017544 DOI: 10.1021/jp907311k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the previous paper of this issue, [Celebre, G.; Ionescu, A. J. Phys. Chem. B doi: 10.1021/jp907310g], following a generalized reaction field approach in the linear response approximation, we were successful in obtaining an analytical compact expression for the mean-field anisotropic orientational potential U(Q-EFG) theoretically experienced by a highly idealized nonionic and apolar solute, considered as a point quadrupole immersed in a uniaxial polarizable continuum medium (model of a nematic solvent comprised of dipolar mesogenic molecules). The term U(Q-EFG) describes the electrostatic interaction between the electric quadrupole of the solute and the electric field gradient induced at the solute by the surrounding medium polarized by the distribution of electric charges representing the quadrupolar solute itself. In the present paper, the obtained potential has been considered as an additional orientational interaction contributing to the solute ordering, besides the well-recognized and very effective "short-range" (size-and-shape-dictated) mechanisms. Since in our theory the solvent is characterized by its dielectric tensor, the model has been widely tested by taking as references the experimental order parameters of several uniaxial and biaxial different small rigid probe molecules (H(2), N(2), acetylene, allene, propyne, benzene, hexafluorobenzene, 1,4-difluorobenzene, and norbornadiene) dissolved in the nematic solvents ZLI1132 (Deltaepsilon >> 0) and EBBA (Deltaepsilon < 0); moreover, the order parameters of the same solutes in the so-called nematic "magic mixture" (45 wt % EBBA + 55 wt % ZLI1132), where the short-range orientational effects are commonly believed to be very dominant, have been conventionally assumed as reference of the absence of electrostatic orientational effects. The experimental order parameters of the treated solutes, obtained in the past by liquid crystal NMR and available from literature, have been then compared with those theoretically predicted by our theoretical approach in order to obtain useful hints about two basic points, (a) the real physical nature of the interactions (other than the "size-and-shape") involved in the orientational mechanisms and (b) the conceptual effectiveness of the suggested mean-field approach in describing this kind of phenomena. Successes and failures of the approach in the predictions are discussed at length, along with their possible reasons and implications.
Collapse
Affiliation(s)
- Giorgio Celebre
- Dipartimento di Chimica, Università della Calabria, v. P. Bucci, I-87036 Rende (CS), Italy.
| | | |
Collapse
|
4
|
Sokolovskii RO, Burnell EE. Orientational order of near D3h solutes in nematic liquid crystals. II. Description via Gay–Berne model with embedded quadrupoles. J Chem Phys 2009; 130:154507. [DOI: 10.1063/1.3104607] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
|
5
|
Elliott Burnell E, ter Beek LC, Sun Z. Mechanisms of solute orientational order in nematic liquid crystals. J Chem Phys 2008; 128:164901. [DOI: 10.1063/1.2900559] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
|
6
|
Lee J, Sokolovskii R, Berardi R, Zannoni C, Burnell E. Orientational order of solutes in liquid crystals: The effect of distributed electric quadrupoles. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.01.071] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
7
|
Zweckstetter M, Hummer G, Bax A. Prediction of charge-induced molecular alignment of biomolecules dissolved in dilute liquid-crystalline phases. Biophys J 2005; 86:3444-60. [PMID: 15189846 PMCID: PMC1304251 DOI: 10.1529/biophysj.103.035790] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alignment of macromolecules in nearly neutral aqueous lyotropic liquid-crystalline media such as bicelles, commonly used in macromolecular NMR studies, can be predicted accurately by a steric obstruction model (Zweckstetter and Bax, 2000). A simple extension of this model is described that results in improved predictions for both the alignment orientation and magnitude of protein and DNA solutes in charged nematic media, such as the widely used medium of filamentous phage Pf1. The extended model approximates the electrostatic interaction between a solute and an ordered phage particle as that between the solute's surface charges and the electric field of the phage. The model is evaluated for four different proteins and a DNA oligomer. Results indicate that alignment in charged nematic media is a function not only of the solute's shape, but also of its electric multipole moments of net charge, dipole, and quadrupole. The relative importance of these terms varies greatly from one macromolecule to another, and evaluation of the experimental data indicates that these terms scale differently with ionic strength. For several of the proteins, the calculated alignment is sensitive to the precise position of the charged groups on the protein surface. This suggests that NMR alignment measurements can potentially be used to probe protein electrostatics. Inclusion of electrostatic interactions in addition to steric effects makes the extended model applicable to all liquid crystals used in biological NMR to date.
Collapse
Affiliation(s)
- Markus Zweckstetter
- Max Planck Institute for Biophysical Chemistry, Am Fassberg, Gottingen, Germany.
| | | | | |
Collapse
|
8
|
Dingemans T, Photinos DJ, Samulski ET, Terzis AF, Wutz C. Ordering of apolar and polar solutes in nematic solvents. J Chem Phys 2003. [DOI: 10.1063/1.1560941] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
9
|
Celebre G, De Luca G. Short-Range Molecular Interactions Governing the Orientational Ordering of Apolar Molecules Dissolved in Nematic Solvents. J Phys Chem B 2003. [DOI: 10.1021/jp026923t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Giorgio Celebre
- Dipartimento di Chimica, Università della Calabria, I-87036 Rende (CS), Italy
| | - Giuseppina De Luca
- Dipartimento di Chimica, Università della Calabria, I-87036 Rende (CS), Italy
| |
Collapse
|
10
|
Syvitski RT, Burnell EE. Dipole-induced ordering in nematic liquid crystals. II. The elusive holy grail. J Chem Phys 2000. [DOI: 10.1063/1.1287336] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
11
|
Syvitski RT, Burnell EE. Multiple quantum and high-resolution NMR, molecular structure, and order parameters of partially oriented ortho and meta dimethyl-, dichloro-, and chloromethylbenzenes codissolved in nematic liquid crystals. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2000; 144:58-73. [PMID: 10783274 DOI: 10.1006/jmre.1999.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We develop a strategy for analyzing complex nuclear magnetic resonance (NMR) spectra of several solutes codissolved in liquid-crystal phases. Spectral parameters of solutes m- or o-xylene were estimated by analyzing 2D multiple-quantum NMR spectra using a modified version of a least-squares fitting routine which adjusts chemical shifts, order parameters, structural parameters, and/or dipolar couplings independently. These estimates were used to facilitate analysis of the high-resolution spectra which contain resonances from many solutes. Calculated spectra of m- or o-xylene were subtracted from the experimental high-resolution spectra leaving resonances from the other solutes readily visible. Accurate spectral parameters of all codissolved solutes were determined from the high-resolution spectra. Order parameters and structural parameters (including vibrationally corrected parameters) of m- and o-xylene, m- and o-chlorotoluene, and m- and o-dichlorobenzene were calculated from the dipolar couplings.
Collapse
Affiliation(s)
- R T Syvitski
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
| | | |
Collapse
|
12
|
|
13
|
McGROTHER SIMONC, GIL-VILLEGAS ALEJANDRO, JACKSON GEORGE. The effect of dipolar interactions on the liquid crystalline phase transitions of hard spherocylinders with central longitudinal dipoles. Mol Phys 1998. [DOI: 10.1080/00268979809483199] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
14
|
Burnell EE, de Lange CA. Prediction from Molecular Shape of Solute Orientational Order in Liquid Crystals. Chem Rev 1998; 98:2359-2388. [PMID: 11848965 DOI: 10.1021/cr941159v] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E. E. Burnell
- Laboratory for Physical Chemistry, University of Amsterdam, Nieuwe Achtergracht 127-129, 1018 WS Amsterdam, The Netherlands
| | | |
Collapse
|
15
|
CELEBRE BG, DE LUCA G, FERRARINI A. Short- and long-range contributions to the ordering of rigid planar solutes dissolved in a 55wt% ZLI1132+ EBBA nematic mixture. Mol Phys 1997. [DOI: 10.1080/002689797169664] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
16
|
|
17
|
Serpi HS, Photinos DJ. The influence of spacer chain conformations on the nematic ordering of main chain polymers. J Chem Phys 1996. [DOI: 10.1063/1.472029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
18
|
|
19
|
Drobny GP, Shilstone GN, Catalano D, Veracini CA, Zimmermann H. The validity of the rotational isomeric state model for short alkyl chains with large substituents: A maximum entropy analysis of the 1H dipolar couplings within the trimethylene group of a liquid crystal molecule. J Chem Phys 1994. [DOI: 10.1063/1.468016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
20
|
Terzis A, Photinos D. Electrostatic interactions in liquid crystals: ordering of rigid solutes in nematic solvents. Mol Phys 1994. [DOI: 10.1080/00268979400101621] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|