Tricarbonyl rhenium(i) complexes with 8-hydroxyquinolines: structural, chemical, antibacterial, and anticancer characteristics.

Twelve tricarbonyl rhenium(i) complexes in the '2 + 1' system with the anionic bidentate N,O-donor ligand (deprotonated 8-hydroxyquinoline (HQ) or its 2-methyl (MeHQ) or 5-chloro (ClHQ) derivative) and neutral N-donor diazoles (imidazole (Him), 2-methylimidazole (MeHim), 3,5-dimethylpyrazole (Hdmpz), and 3-phenylpyrazole (HPhpz)) were synthesized: [Re(CO)(L)L] (L = Q, MeQ, ClQ; L = Him, MeHim, Hdmpz, HPhpz). Their crystal structures were determined by the scXRD method, compared with the DFT-calculated ones, and characterized by analytical (EA) and spectroscopic techniques (FT-IR, NMR, and UV-Vis) interpreted with DFT and TD-DFT calculations. Most of the Re(i) complexes did not show relevant antibacterial activity against Gram-negative and Gram-positive bacterial strains.

VCD spectra of chiral naphthalene-1-carboxamides in the solid-state.

The VCD spectra of chiral 2,3-dihydro-1H-benzo[de]isoquinolin-1-one (8-substituted naphthalene-1-carboxamide, BIQ) were studied in KBr pellets. The X-ray diffractometry revealed that the Me, Ph, and pClPh BIQs crystalize in the monoclinic P2, while nBu, pMePh, and oMeOPh BIQs in the orthorhombic P222 space group. Only the Me-BIQ crystal exhibits the presence of cyclic amide dimers, while the others contain chains of the amid group hydrogen bonds.

Differentiation of solvatomorphs of active pharmaceutical ingredients (API) by solid-state vibrational circular dichroism (VCD).

Here, we present the new application of solid-state Vibrational Circular Dichroism (VCD) spectroscopy to differentiate several dutasteride (DS) solvatomorphs - the model active pharmaceutical ingredient (API). Several crystalline DS hydrochloride hydrates solvated with methanol, ethanol, acetonitrile, acetone, and acetic acid were prepared. In contrast to almost identical IR spectra, the VCD ones were very sensitive to changes in the sample composition.

Rearrangement of thiazolidine derivatives - a synthesis of a chiral fused oxathiane-γ-lactam bicyclic system.

Reaction of L-cysteine with carbonyl compounds leads to thiazolidine derivatives which undergo a stereoselective conversion to two types of chiral bicyclic products bearing two or three stereogenic centers, including the first fused oxathiane-γ-lactam system.

UV-vis and ECD spectroelectrochemistry of atropisomeric naphthalenediimide derivative.

The UV-vis and ECD spectroelectrochemistry (SEC) of a chiral binaphthalenylamine derivative of the N-butyl naphthalenediimide (NDIB-NH) enantiomers were applied to measure UV-vis and ECD spectra of NDIB-NH radicals and dianion formed in the reduction and oxidation processes observed in cyclic voltammetry (CV). The CV curves and EPR spectroelectrochemistry enabled us to establish conditions at which a radical-anion [NDIB-NH]̇, a dianion [NDIB-NH], and a radical-cation [NDIB-NH]̇ are formed. The DFT restricted open-shell CAM-B3LYP-D3/def2TZVP/PCM calculations demonstrated that in the radical-anion [NDIB-NH]̇, spin is spread over the NDI system while in the radical-cation [NDIB-NH]̇ it is spread over the aminonaphthalene moiety.

Chirality transfer observed in Raman optical activity spectra.

Chirality transfer (also called induced chirality) is a phenomenon present in chiroptical spectra that manifests itself as a new band or bands of an achiral molecule interacting with a chiral one. In the Raman optical activity (ROA) spectroscopy, the bands of achiral solvents have been recently observed, but the latest papers have shown that they corresponded to the new ECD-Raman (eCP-Raman) effect. Here, we show an unambiguous example of chirality transfer observed in the ROA spectra.

New chiral ECD-Raman spectroscopy of atropisomeric naphthalenediimides.

In this study, we found that a recently discovered ECD-Raman effect dominated over the natural Raman optical activity in a series of atropisomeric naphthalenediimides, and we investigated the kind of information about the molecular structure that could be obtained from the spectra. The ECD-Raman effect is polarised Raman scattering modulated by electronic circular dichroism. We showed that the spectra significantly depended on the substitution of the solute and/or the change of the solvent.

The solid state VCD of a novel N-acylhydrazone trifluoroacetate.

A novel N-acylhydrazone with pharmaceutical importance was subject of structural and IR/VCD investigations in the solid state. In the crystal structure, dimers of anion-cation pairs are stabilized by H-bonding and ionic interactions. Some less common interaction types, like C=N···C-NH (σ-hole) interactions, hydrazone-aromatic interactions and dispersive contacts of the CF groups are also present in the crystal.

Enantioselective sensing of (S)-Thalidomide in blood plasma with a chiral naphthalene diimide derivative.

Fast, simple in use and highly effective voltammetric enantiosensor dedicated for determination of thalidomide (TD) enantiomers (especially towards the toxic (S)-enantiomer) in blood plasma is still desirable. Here we have proven that newly synthesized chiral naphthalene diimide (NDI) derivatives are excellent electroactive materials for TD enantiosensors. The recognition process relies on the specific interaction between the chiral NDI receptor and the thalidomide enantiomer of the opposite configuration.

Chiral Lanthanide Complexes with l- and d-Alanine: An X-ray and Vibrational Circular Dichroism Study.

A whole series of [Ln(HO)(Ala)] dimeric cationic lanthanide complexes with both L- and D-alanine enantiomers was synthesized. The single-crystal X-ray diffraction at 100 and 292 K shows the formation of two types of dimers ( and ) in crystals. Between the dimer centers, the alanine molecules behave as bridging (-O,O'-) and chelating bridging (-O,O,O'-) ligands.

Revision of the Structure of N, O-Diacetylsolasodine. Unusual Epimerization at the Spiro Carbon Atom during Acetylation of Solasodine.

The steroidal alkaloid solasodine (1) undergoes inversion of configuration at the C-22 spiro atom when treated with acetic anhydride-pyridine at ambient temperature. The basic solvolysis of the N, O-diacetyl derivative (2) reverses the reaction, yielding the starting solasodine (1). The mechanisms of both processes (acetylation and deacetylation) were studied in terms of possible reaction pathways.

Solvation of 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol revealed by circular dichroism: a case of chromane helicity rule breaking.

The primary goal of this work is to clarify why 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol {(S)-TMChM} deviates from the chromane helicity rule under solvent change. The rule, applicable to determining the absolute configuration of molecules containing the chromane chromophore, binds the sign of the 1Lb Cotton effect (CE) with the helicity of the dihydropyran ring. In case of TMChM, however, this CE exhibits extreme solvent dependence: it is negative in non-coordinating solvents and positive in coordinating ones, irrespective of the helicity of the heterocyclic ring.

The Vibrational Circular Dichroism Pattern of the ν(C=O) Bands in Isoindolinones.

The IR and vibrational circular dichroism (VCD) spectra of both enantiomers of Me-, iPr-, nBu-, Ph-, and CH Ph-substituted isoindolinones in solution and KBr pellets were measured and interpreted by DFT calculations. The spectra in solution revealed no important differences in the C=O stretching vibration region while the interpretation of very distinct spectra taken in pellets required determining the crystal structures. The studied compounds crystallized in the P2 2 2 (Me, iPr, CH Ph), P3 (nBu), and P2 (Ph) space groups.

Circular dichroism spectroscopy and DFT calculations in determining absolute configuration and E/Z isomers of conjugated oximes.

The primary purpose of this work was to demonstrate the suitability of circular dichroism (CD) spectroscopy in stereochemical studies of α,β-unsaturated oximes, with particular emphasis on determination of E and Z geometry of the oxime double bond. As models for this study, O-phenyl and O-triphenylmethyl (trityl) oximes of 4-hydroxy-2-methylcyclopent-2-en-1-one were selected. These model compounds differ in both absolute configuration at C4 carbon atom and E-Z configuration of the oxime double bond.

Chiral Thiophene Sulfonamide-A Challenge for VOA Calculations.

Two enantiomers of 2-methyl-N-(1-thien-2-ylethyl)propane-2-sulfonamide (TSA) were synthesized, and their VCD, ROA, IR, and Raman spectra were registered. The solved (S)-TSA X-ray structure shows a disorder connected to the presence of two TSA conformers differing by a slight rotation of the thiophene ring. Two molecules in the unit cell of the monoclinic P2 crystal form a net of NH···OS and C*H···OS hydrogen bonds.

Exploring the Sponge Consortium Plakortis symbiotica-Xestospongia deweerdtae as a Potential Source of Antimicrobial Compounds and Probing the Pharmacophore for Antituberculosis Activity of Smenothiazole A by Diverted Total Synthesis.

Fractionation of the bioactive CHCl-MeOH (1:1) extracts obtained from two collections of the sponge consortium Plakortis symbiotica-Xestospongia deweerdtae from Puerto Rico provided two new plakinidone analogues, designated as plakinidone B (2) and plakinidone C (3), as well as the known plakinidone (1), plakortolide F (4), and smenothiazole A (5). The structures of 1-5 were characterized on the basis of 1D and 2D NMR spectroscopic, IR, UV, and HRMS analysis. The absolute configurations of plakinidones 2 and 3 were established through chemical correlation methods, VCD/ECD experiments, and spectroscopic data comparisons.

Modelling the matrix shift on the vibrational frequency of ThO by DFT-D3 calculations.

Benchmark calculations with a goal to find dispersion-corrected DFT-D3 methods suitable for a reliable estimation of matrix shifts on the vibrational frequency were carried out on the ThO molecule in three rare gas (Rg = Ne, Ar, and Kr) matrices. The matrices were modelled by the explicit approach, in which a single and a double shell of Rg atoms around ThO was considered. The selection of exchange-correlation functionals was based on test calculations on triatomic ThO⋯Rg models.

Reassignment of the absolute configuration of plakinidone from the sponge consortium using a combination of synthesis and a chiroptical approach.

Recent work by Wu et al. in connection with the first synthesis of the marine natural product plakinidone revealed that the most salient feature of its purported structure, a six-membered perlactone moiety, was in fact a five-membered lactone, i.e.

Prediction of (L)-methionine VCD spectra in the gas phase and water solution.

In this paper we provide a computational study of the l-methionine conformational landscape and VCD spectra in the gas phase and a water environment simulated by implicit PCM and the hybrid model, i.e., a combination of explicit "microsolvation" and implicit models.

Chirality measures of α-amino acids.

To measure molecular chirality, the molecule is treated as a finite set of points in the Euclidean R(3) space supplemented by k properties, p(1)((i)), p(2)((i)), ...

On chirality transfer in electron donor-acceptor complexes. A prediction for the sulfinimine···BF3 system.

Stabilization energies of the electron donor-acceptor sulfinimine···BF(3) complexes calculated at either the B3LYP/aug-cc-pVTZ or the MP2/aug-cc-pVTZ level do not allow to judge, whether the N- or O-atom in sulfinimine is stronger electron-donor to BF(3) . The problem seems to be solvable because chirality transfer phenomenon between chiral sulfinimine and achiral BF(3) is expected to be vibrational circular dichroism (VCD) active. Moreover, the bands associated with the achiral BF(3) molecule are predicted to be the most intense in the entire spectrum.

On stability, chirality measures, and theoretical VCD spectra of the chiral C58X2 fullerenes (X = N, B).

The stability of all 23 C(58)N(2) and C(58)B(2) heterofullerenes in the singlet and triplet states was determined at the B3LYP/6-31G** level. In equilibrium mixture the achiral (1,4) C(58)N(2) isomer would be populated in ca. 95.