On the Origin of the Color in the Solid State. Crystal Structure and Optical and Magnetic Properties of 4-Cyanopyridinium Hydrogensquarate Monohydrate

Abstract

The novel hydrogensquarate salt of 4-cyanopyridine was synthesized, and its structure and properties were elucidated in detail spectroscopically, thermally, and structurally, using single-crystal X-ray diffraction, linear-polarized solid-state IR spectroscopy, UV spectroscopy, TGA, DSC, DTA, and positive and negative ESI MS as well as 1H and 13C NMR methods. Quantum chemical methods were used to calculate the electronic structure, vibrational data, and electronic spectra. 4-Cyanopyridinium hydrogensquarate monohydrate crystallizes in the space group P and exhibits a layered structure with molecules linked by intermolecular NH...O(HSq-) (2.651 A) and HOH...O(HSq-) (2.792 and 2.563 A) hydrogen bonds with participation of cations, anions, and the solvent molecule. The formation of stable layers of the type (2HSq-.2H2O)n and the observation of a red color in the solid state is discussed. The optical and magnetic properties were elucidated in comparison to the data for neutral 4-cyanopyridine as well as its four known salts.

Extraction of trace acetylspiramycin in real aqueous environments using aqueous two-phase system of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and phosphate

“…In this system, the protonation effect of ASPM also promoted ASPM into the [Bmim]BF 4 -rich phase. The protonation processes of similar systems have been studied by IRspectroscopy [22,23]. Under optimum conditions, the method discussed in this work could be satisfactorily applied to extract and separate ASPM in actual water samples.…”

Supramolecular structure of the 1:2 complex of 1,4-dimethylpiperazine mono-betaine with squaric acid

“…Table 1. 21 , which proves a significant role of the hydrogen bonds in the molecular structure of the complexes.…”

“…According to the X-ray data, there are two medium strong OZH· · ·O hydrogen bonds of 2.527(4) and 2.516(4) Å . The OZH stretching vibrations appear as a broad band in the range of 3000-2000 cm 21 centred at 2460 cm 21 . This band shifts to the lower wave numbers in the spectrum of the deuterated sample.…”

Tert-butyl esters of 2,3-diaryl-3-arylaminopropanoic acids - stereoselective synthesis, isolation, spectroscopic and structural elucidation

“…Nonpolarized solid-state IR spectra were recorded using the KBr pellets technique. The oriented samples were obtained as a suspension in a nematic liquid crystal (MLC 6815, Merck) with the presence of an isolated nitrile stretching IR-band at about 2245 cm -1 additionally serving as an orientation indicator [9][10][11][12][13][14][15][16][17] . Ultraviolet (UV-) spectra were recorded on Tecan Safire Absorbance/Fluorescence XFluor 4 V 4.40 spectrophotometer operating between 190 and 900 nm, using solvent ethanol (Uvasol, Merck product) at a concentration of 2.5.10 -5 M in 0.921 cm quarz cells.…”

“…TD DFT and CIS calculations are performed for elucidation of the theoretical optical properties of the seven compounds in solution. The theoretical approach is described in [9][10][11][12][13][14][15][16][17] .…”