IR Spectra Of Crystals Research Articles

Study of p-(3-carboxymethyl-1-adamantyl)calix[4]arene and tetrapropoxy-p-(3-carboxymethyl-1-adamantyl)calix[4]arene by vibrational spectroscopy and DFT

The IR and Raman spectra of p-(3-carboxymethyl-1-adamantyl)calix[4]arene (1) and tetrapropoxy-p-(3-carboxymethyl-1-adamantyl)calix[4]arene (2) were studied. In the IR spectra of crystals and solutions of calixarenes, there is no band of stretching vibrations of free OH groups. In the IR spectrum of compound 1 in the crystalline state, an intense wide band is observed at 3187 cm−1. In the IR spectrum of a dilute solution in CCl4, this band shifts to 3118 cm−1. The carboxyl groups form cyclic dimer or tetramer complexes.The formation of dimers of carboxyl groups is more favorable than for cyclic tetramers. The energy difference is 33.8 and 53.0 kJ/mol in compounds 1 and 2, respectively. The calculation showed that molecules 1 and 2 of dimeric and tetrameric complexes assume the cone conformation. The molecules of compound 2 are in the cone conformation even in the absence of hydrogen bonds along the lower rim.

Some specific features of spectral bands location in the infrared spectra of crystals and liquids

A cluster model of condensed matter has been used to demonstrate that the observed peaks in the IR spectra of crystals and liquids correspond to the most stable cluster structures with the number of particles forming series of Fibonacci numbers. The relationship between the frequencies obeys the golden section rule.

Synthesis and crystal structure of [UO2(OH)(CO(NH2)2)3]2(ClO4)2

The complex [UO2(OH)(CO(NH2)2)3]2(ClO4)2 (I) was synthesized. A single crystal X-ray diffraction study showed that compound I crystallizes in the triclinic system with the unit cell parameters a = 7.1410(2), b = 10.1097(2), c = 11.0240(4) A, α = 104.648(1)°, β = 103.088(1)°, γ = 108.549(1)°, space group \(P\bar 1\), Z = 1, R = 0.0193. The uranium-containing structural units of the crystals are binuclear groups [UO2(OH)· (CO(NH2)2)3]22+ belonging to crystal-chemical group AM2M31 [A = UO22+, M2 = OH−, M1 = CO(NH2)2] of uranyl complexes. The crystal-chemical analysis of nonvalent interactions using the method of molecular Voronoi-Dirichlet polyhedra was performed, and the IR spectra of crystals of I were analyzed.

Self-Assembly of Hydrogensquarates: Crystal Structures and Properties

The self-assembly of the hydrogensquarates is elucidated by means of linear-polarized infrared (IR-LD) spectroscopy of oriented colloids in nematic host and the so-called reducing-difference procedure for polarized IR-LD spectra interpretation. The scopes and limitation are discussed on five novel derivatives of squaric acid and its anions, that is, 2-chloro-3-aminopyridinium hydrogensquarate (1), bis (1,2,3,4-tetrahydroquinolinium) squarate (2), bis hydrogensquarate dihydrate salt of 4-(aminomethyl)pyridine (3), N-(2-ammoniumethyl)-piperazinium monohydrate hydrogensquarate squarate (4), and 3-nitropyridinium hydrogensquarate monohydrate (5), respectively. The structures of these compounds 1-5 were solved by means of single-crystal X-ray diffraction, and the crystallographic data were used for the experimental elucidation of the corresponding IR spectra of crystals with respect to studying Fermi-resonance (FR), Davydov splitting (DS), and Fermi-Davydov (FD) as well as Evans' hole effects. The various motifs for self-assembly of squaric acid and its anions in the organic crystals are discussed together with their IR-spectroscopic properties.

Vibrational spectra and conformational composition of ethylene glycol dinitrate in solid phases

8. J. A. Barltrop and J. D. Coyle, Excited States in Organic Chemistry [Russian transla- tion], Moscow (1978), pp. 67"70. 9. I. S. Ioffe and V. F. Otten, Zh. Organ. Khim., 32, No. 4, 1196-1201 (1962). i0. I. S. Ioffe and V. F Otten, Zh. Organ. Khim., i, No. 2, 343-346 (1965). ii. Yu. Yu. Lur'e, Handbook on Analytical Chemistry [in Russian], Moscow (1979), p. 322. 12. B. Stevens, N. Conneily, and P. Suppan, Spectrochim. Acta, 2-2, No. 12, 2121-2122 (1966). 13. Sharma Ashutash and M. K. Machwe, Curr. Sci. (India), 5_~i, No. 13, 657-659 (1982). 14. M. D. Galanin, A. A. Kut'enkov, V. N. Smorchkov, et al., Opt. Spektrosk., 53, No. 4, 683-689 (1982). 15. V. Ya. Artyukhov, R. T. Kuznetsova, and R. M. Fofonova, Zh. Prikl. Spektrosk., 37, No. 4, 576-580 (1982). 16. F. V. Schaefer (ed.), Dye Lasers, Springer, New York (1977). VIBRATIONAL SPECTRA AND CONFORMATIONAL C~9OSITION OF ETHYLENE GLYCOL DINITRATE IN SOLID PHASES G. A. Beresneva, L. V. Khristenko, UDC 539.194.01 S. V. Krasnoshchekov, and Yu. A. Pentin The authors of [i] studied the vibrational spectra of ethylene glycol dinitrate (EGDN) and showed that in the liquid state this compound consists of a mixture of conformers, while in the crystalline state it exists in the form of two modifications: a metastable one (crystal II), obtained by intense supercooling the liquid, and a stable modification (crystal I) obtained by either slowly cooling the liquid, or by heating the metastable modification to a temperature of -50~ If we assume that in a restrained internal rotation around the C--C and C--O bonds, the "staggered" conformations will be stable, while the --C-~NO= groups are planar, then EGDN can exist in the form of ten different nuclear equilibrium configurations. Figure i shows these possible conformations of EGDN. The authors of [i] suggested that each of the solid modifications is formed by only one of the ten possible conformers, which were identified from the data of rotation isomerism of ethyl nitrate [2] and the results of vibrational calculation carried out in [3], using force constants obtained by the MINDO/2 method. In this present work, the IR spectra of crystals I and II were recorded on a Bruker Fourier-type spectrometer with a higher,resolution than that obtained in [i], including the region below 400 cm -I, in which the IR spectra of crystals have not yet been studied. Figure 2 shows the IR spectra of a vitreous EGDN and two of its crystalline modifications (I and II). In the spectrum of crystal II in the 100-900 cm -I region, a region of skeletal stretch- ing and deformational vibrations, which are most sensitive to rotation isomerism, the number of bands exceeds that required for one nuclear configuration at equilibrium. On crystal II § crystal I transition, the bands at 213, 390, 588, 662, 715, 862, 928, i036,'1237, 1392, 1431, 1460, and 1646 cm -i disappear. Bands at 364, 405, 581, 656, 680, 937, 1044, 1232, 1309, 1396, 1422, 1449, and 1666 cm -~, with a low intensity in the spectrum of crystal II, become markedly more intense, and the number of bands in the spectrum of crystal I in the 100-900 cm -i region corresponds to the number of bands for one Conformer. These facts indicate that crystal II is formed by at least two conformers, and crystal I by one conformer, and the conformer forming crystal I is also included in the composition of crystal II. For a more reliable identification of the conformers forming crystals I and II, we calculated the frequencies and forms of normal vibrations of all the ten possible conformers of EGDN. The calculations were carried out in an independent system of local symmetry co- ordinates, by a standard method [4]. The natural coordinates introduced, which are repre- Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 48, No. 6, pp. 946-952, June, 1988. Original article submitted April 8, 1987. 614 0021-9037/88/4806-0614512.50 9 1988 Plenum Publishing Corporation