Dynamical disorder in 2-methyl-4-nitroaniline and its deuterated analogue crystals studied by Fourier transform infrared and nuclear magnetic resonance

Photoactive metal-organic framework as a bifunctional material for 4-hydroxy-4'-nitrobiphenyl detection and photodegradation of methylene blue

Environmental pollution resulting from organic pollutants is becoming an overwhelming problem throughout the world, and how to efficiently detect or eliminate these organic pollutants remains an important issue for environmental protection. Herein, a cadmium(ii)-based MOF, Cd-TCAA, was successfully prepared by the hydrothermal reaction of 4,4',4''-tricarboxyltriphenylamine (H3tca), (E)-1,2-di(pyridin-4-yl)diazene (abp) and cadmium nitrate. Because the H3tca moiety is a typically versatile functional material that exhibits good hole-transporting capabilities, efficient light harvesting, and excellent electron-donating properties, this novel photoactive metal-organic framework operates as a bifunctional material for the detection and degradation of organic pollutants. It exhibits excellent selectivity and sensitivity towards 4-hydroxy-4'-nitrobiphenyl (HNBP) with a detection limit of 50 nM in solution, and represents the first example of a MOF-based sensor for the detection of HNBP. The photocatalytic activity of Cd-TCAA was also determined by investigating the photo-induced degradation of methylene blue (MB). Cd-TCAA has the advantages of excellent catalytic activity, stability, and recyclability.

Comparison of hydrogen bonds and diverse weak interactions of the nitro group in 2-methyl-4-nitroanilinium nitrate, bisulfate and two hexafluoridosilicates: elementary graph-set approach

Crystal structures of (H2m4na)NO₃ (1), (H2m4na)HSO₄ (2), (H2m4na)₂SiF₆ (3) and (H2m4na)₂SiF₆·2H₂O (4), where 2m4na = 2-methyl-4-nitroaniline, are presented. Two layers of interactions occur in the structures, N-H...O/F hydrogen bonds and interactions with the nitro group. Although diverse, hydrogen-bonding patterns are compared with each other by means of interrelations among elementary graph-set descriptors and descriptors of hydrogen-bonding patterns. Using mathematical relations, the gradual expansion of the ring patterns was shown in the crystal structures. Parallel and perpendicular arranged nitro groups form weak π(N)_NO2...π(O)_NO2 and π(N)_NO2...O_NO2 interactions, respectively. The π_NO2...π_ring interaction has an impact to the stabilization of parallel oriented nitro groups. Generally, weak interactions constructed by the nitro group occur in the studied crystals as follows: π(N)_NO2...π(O)_NO2, π_ring...π_ring, C-H...O (1); π(N)_NO2...π(O)_NO2, π(N)_NO2...O_NO2 (2); π(N)_NO2...π(O)_NO2, π(N)_NO2...O_NO2 (3); C-H...O (4).

A metal–organic framework with a 9-phenylcarbazole moiety as a fluorescent tag for picric acid explosive detection: collaboration of electron transfer, hydrogen bonding and size matching

An electron-rich luminescent metal–organic framework, Zn–PDA, displaying high selectivity in detection of picric acid explosive as a fluorescent sensor is reported.

Hydrogen bond dynamics in crystalline β-9-anthracene carboxylic acid--a combined crystallographic and spectroscopic study

We compare results from single crystal X-ray diffraction and FTIR spectroscopy to elucidate the nature of hydrogen bonding in β-9-anthracene carboxylic acid (β-9AC, C(15)H(10)O(2)). The crystallographic studies indicate a disorder for the protons in the cyclic hydrogen bond. This disorder allows the determination of the energy difference between two proton sites along the hydrogen bond. The temperature dependent Fourier transform infrared spectroscopy (FTIR) underpins the crystallographic results. The combination of both methods allows the estimation of a one-dimensional potential curve describing the OH-stretching motion. The dynamical properties of the proton transfer along the hydrogen bond are extracted from this potential. The work presented here has profound implication on future studies of photochemical dynamics of crystalline β-9AC, which can deliver a deeper understanding of the mechanism of photochemical driven molecular machines and the optical and electronic properties of molecular organic semiconductors.