Benjamin P. Dailey

Bio: Benjamin P. Dailey is an academic researcher from Columbia University. The author has contributed to research in topics: Liquid crystal & Anisotropy. The author has an hindex of 18, co-authored 48 publications receiving 2186 citations.

The 1H chemical shielding anisotropies of acetylene and fluoroform, as measured in a smectic liquid crystal solvent

Abstract: A new method of measuring the chemical shielding anisotropies of C2H2 and CHF3 is reported, which employs the use of a smectic phase liquid crystal solvent. The anisotropies obtained with this method are in good agreement with theoretical calculations. Δσ values are reported for acetylene and fluoroform as being +14·2 ± 0·3 and +9·4 ± 0·2 p.p.m. respectively. Large magnitudes of the ordering parameter S zz are obtained through the use of this method, which also essentially eliminates most effects due to temperature and phase changes. The method enables one to obtain the chemical shielding anisotropy from measurements in the smectic phase only and at a single temperature.

19F and 31P magnetic shielding anisotropies and the F–P–F bond angle of PSF3 in a smectic liquid crystal solvent

Abstract: The 19F and 31P magnetic shielding anisotropies of thiophosphoryl fluoride have been determined at a single temperature and in the smectic liquid crystal phase solely, using 4‐n‐octyloxybenzylidene‐4′ amino acetophenone (OBAA) as an orienting solvent. Measurements of the F–P–F bond angle are also reported. The absolute sign of the indirect P–F spin–spin coupling constant is found to be negative, and the anisotropy in this quantity is assumed to be negligible. In addition, the 31P spectra of phosphorus trifluoride, dissolved in a smectic liquid crystal solvent, is also investigated in this study, and the value of Δσ obtained in the smectic phase for PF3 is found to be in disagreement with the previous value measured in the nematic liquid crystal phase.

Deuteron quadrupole coupling constants in CD3F and 1,3,5‐C6D3F3

Abstract: The deuteron quadrupole coupling constants in the deuterated methyl fluoride and 1,3,5‐trifluorobenzene molecules have been determined from nematic phase studies using a pulsed FT NMR spectrometer. The values obtained in the molecular symmetry axis system are as follows: χzz = −47.8±1.5 kHz (in CD3F) and χzz = −94.4±0.7 kHz (in 1,3,5‐C6D3F3). If the field gradient tensor is assumed to be diagonal in the C–D bond axis system, the values of the coupling constants referred to the C–D bond are given by χCD = 133±7 kHz (in CD3F, η = 0.03±0.03) and χCD = 180±3 kHz (in 1,3,5‐C6D3F3, η = 0.05±0.01).

1,3-Dipolar Cycloadditions. Past and Future†

Abstract: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available. The 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles. Here the “1,3-dipole”, which can only be represented by zwitterionic octet resonance structures, combines in a cycloaddition with a multiple bond system – the “dipolarophile” – to form an uncharged five-membered ring. Although numerous individual examples of this reaction were known, some even back in the nineteenth century, fruitful development of this synthetic principle has been achieved only in recent years.

Deuterium magnetic resonance: theory and application to lipid membranes.

Abstract: Proton and carbon-13 nmr spectra of unsonicated lipid bilayers and biological membranes are generally dominated by strong proton–proton and proton–carbon dipolar interactions. As a result the spectra contain a large number of overlapping resonances and are rather difficult to analyse. Nevertheless, important information on the structure and dynamic behaviour of lipid systems has been provided by these techniques (Wennerstrom & Lindblom, 1977).

1.3‐Dipolare Cycloadditionen Rückschau und Ausblick

Abstract: Einer sehr grosen Zahl spezieller Synthesewege in die heterocyclische in die Reihe steht ein nur bescheidener Satz an Aufbaumethoden von allgemeiner Verwendbarkeit gegenuber. Eine erstaunliche Anwendungsbreite bei der Synthese funfgliedriger Heterocyclen kommt der 1.3-Dipolaren Addition zu. Dabei vereinigt sich der nur mit zwitterionischen Oktett-Grenzformeln wiederzugebende „1.3-Dipol” mit einem Mehrfachbindungssystem, dem „Dipolarophil”, in einer Cycloaddition zum ladungsfreien funfgliedrigen Ring. Wenngleich die Kenntnis zahlreicher Einzelbeispiele bis ins vorige Jahrhundert zuruckreicht, gelangte das Syntheseprinzip erst in den letzten Jahren zu fruchtbarer Entfaltung.

A new criterion for the determination of molecular structures from ground state rotational constants

Abstract: Kraitchman has shown that a single isotopic substitution on an atom is sufficient to determine directly the coordinates of that atom with respect to the principal axes of the original molecule. Kraitchman's formulas represent exact solutions of the equations for the equilibrium moments of inertia. However, the effects of the zero‐point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0. These coordinates have here been called r (substitution) or rs, and it is found that rs≃(r0+re)/2, and Is= ∑ imirsi2≃(I0+Ie)/2.In the usual method of solution, the coordinate of one atom is determined from the equation for I0, and therefore the difference I0—Is must be made up by this one coordinate. This introduces a large error in the structures normally determined from ground state constants, and results in variations of 0.01 A in structures determined from different sets of isotopic species. If instead, we obtain the structure on...