N 2,N 2,N 6,N 6-Tetra­kis(2,3,4,5,6-penta­fluoro­benzo­yl)pyridine-2,6-diamine

The title compound, C33H3F20N3O4, is a highly fluorinated organic imide that was isolated as an unexpected product from the reaction of 2,6-diamino­pyridine with 2,3,4,5,6-penta­fluoro­benzoyl chloride in a 1:2 molar ratio. The mol­ecule is located on a twofold axis and one of its symmetry-independent 2,3,4,5,6-penta­fluoro­benzoyl groups is disordered over two sets of sites, the occupancy of the major component being 0.773 (3). In the major component, the dihedral angle between the perfluoro­phenyl groups is 63.64 (10)°, and these groups form dihedral angles of 67.14 (7) and 21.1 (2)° with the pyridine core. Short inter­molecular C—H⋯O and C—H⋯N contacts are found in the crystal structure

(Z)-Ethyl 2-oxo-3-(1,2-dihydroquinolin-2-yl­idene)propano­ate

Both independent mol­ecules in the asymmetric unit of the tautomeric title compound, C14H13NO3, a synthetic product obtained from 2-lithio­methyl­quinoline and diethyl oxalate, crystallize in the enaminone form with a Z configuration around the double bond. Intra­molecular N—H⋯O hydrogen bonds occur, generating an S(6) graph-set motif. In the crystal, weak inter­molecular C—H⋯O and π–π stacking inter­actions [centroid–centroid distances = 3.7020 (14)–3.7429 (13)Å] define a three-dimensional supra­molecular network

N-(2-Benzoyl-4-chloro­phen­yl)-4-chloro­benzene­sulfonamide

The title compound, C19H13Cl2NO3S, is an N-aryl­sulfonyl derivative of 2-amino-5-chloro­benzophenone. The compound is biologically active and shows potential to be utilized as an inhibitor of CCR2 and CCR9 receptor functions. In the crystal structure, there is an intra­molecular N—H⋯O hydrogen bond between the amide and carbonyl groups. The benzoyl and 4-chloro­phenyl groups form intra­molecular and inter­molecular face-to-face contacts, with a dihedral angle of 10.6 (1)° between their mean planes in both cases, and centroid–centroid separations of 4.00 (1) and 4.25 (1) Å for the intra- and inter­molecular inter­actions, respectively

Benchmarking Density Functional Approximations for Excited-State Properties of Fluorescent Dyes

This study presents an extensive analysis of the predictive power of time-dependent density functional theory in determining the excited-state properties of two groups of important fluorescent dyes, difluoroboranes and hydroxyphenylimidazo[1,2-a]pyridine derivatives. To ensure statistically meaningful results, the data set is comprised of 85 molecules manifesting diverse photophysical properties. The vertical excitation energies and dipole moments (in the electronic ground and excited states) of the aforementioned dyes were determined using the RI-CC2 method (reference) and with 18 density functional approximations (DFA). The set encompasses DFAs with varying amounts of exact exchange energy (EEX): from 0% (e.g., SVWN, BLYP), through a medium (e.g., TPSSh, B3LYP), up to a major contribution of EEX (e.g., BMK, MN15). It also includes range-separated hybrids (CAM-B3LYP, LC-BLYP). Similar error profiles of vertical energy were obtained for both dye groups, although the errors related to hydroxyphenylimidazopiridines are significantly larger. Overall, functionals including 40–55% of EEX (SOGGA11-X, BMK, M06-2X) ensure satisfactory agreement with the reference vertical excitation energies obtained using the RI-CC2 method; however, MN15 significantly outperforms them, providing a mean absolute error of merely 0.04 eV together with a very high correlation coefficient (R2 = 0.98). Within the investigated set of functionals, there is no single functional that would equally accurately determine ground- and excited-state dipole moments of difluoroboranes and hydroxyphenylimidazopiridine derivatives. Depending on the chosen set of dyes, the most accurate μGS predictions were delivered by MN15 incorporating a major EEX contribution (difluoroboranes) and by PBE0 containing a minor EEX fraction (hydroxyphenylimidazopiridines). Reverse trends are observed for μES, i.e., for difluoroboranes the best results were obtained with functionals including a minor fraction of EEX, specifically PBE0, while in the case of hydroxyphenylimidazopiridines, much more accurate predictions were provided by functionals incorporating a major EEX contribution (BMK, MN15)

Conformational and Tautomeric Control by Supramolecular Approach in Ureido-N-iso-propyl,N’-4-(3-pyridin-2-one)pyrimidine

Ureido-N-iso-propyl,N’-4-(3-pyridin-2-one)pyrimidine (1) and its 2-methoxy pyridine derivative (1Me) has been designed and prepared. The conformational equilibrium in urea moiety and tautomerism in the pyrimidine part have been investigated by variable temperature and 1H NMR titrations as well as DFT quantum chemical calculations. The studied compounds readily associate by triple hydrogen bonding with 2-aminonaphthyridine (A) and/or 2,6-bis(acetylamino)pyridine (B). In 1, the proton is forced to 1,3-tautomeric shift upon stimuli and keeps it position, even when one of the partners in the complex was replaced by another molecule. The observed tautomerism controlled by conformational state (kinetic trapping effect) opens new possibilities in molecular sensing that are based on the fact that reverse reaction is not preferred.peerReviewe