This study presents a new 5-methoxy-1H-indole-2-carboxylic acid (MI2CA) polymorph investigated by single-crystal X-ray diffraction, infrared spectroscopy, and density functional theory (ωB97X-D) ...calculations employing two basis sets (6-31++G(d,p) and aug-cc-pVTZ). The compound crystallizes in the monoclinic system, space group P21/c (a = 4.0305(2) Å, b = 13.0346(6) Å, c = 17.2042(9) Å, β = 91.871(5)°, Z = 4). In the crystalline structure, the formation of cyclic dimers via double hydrogen bonds O−H⋯O between MI2CA molecules was observed. Interactions between the NH groups of the indole rings and the adjacent methoxy groups, as well as C–H⋯O contacts, significantly influence the spatial arrangement of molecules. The results from DFT calculations, including dimeric and trimeric structures, agree well with the experimental structural and spectroscopic data. Analysis of the infrared spectra confirms the conclusions drawn from X-ray diffraction studies and reveals differences between the IR spectra of the newly obtained polymorph and that reported earlier in the literature. This comprehensive study sheds some light on the MI2CA polymorphism and is important for a potential pharmacological applications of this compound.
This study presents a new 5-methoxy-1H-indole-2-carboxylic acid (MI2CA) polymorph investigated by single-crystal X-ray diffraction, infrared spectroscopy, and density functional theory (ωB97X-D) ...calculations employing two basis sets (6-31++G(d,p) and aug-cc-pVTZ). The compound crystallizes in the monoclinic system, space group P2sub.1/c (a = 4.0305(2) Å, b = 13.0346(6) Å, c = 17.2042(9) Å, β = 91.871(5)°, Z = 4). In the crystalline structure, the formation of cyclic dimers via double hydrogen bonds O−H⋯O between MI2CA molecules was observed. Interactions between the NH groups of the indole rings and the adjacent methoxy groups, as well as C–H⋯O contacts, significantly influence the spatial arrangement of molecules. The results from DFT calculations, including dimeric and trimeric structures, agree well with the experimental structural and spectroscopic data. Analysis of the infrared spectra confirms the conclusions drawn from X-ray diffraction studies and reveals differences between the IR spectra of the newly obtained polymorph and that reported earlier in the literature. This comprehensive study sheds some light on the MI2CA polymorphism and is important for a potential pharmacological applications of this compound.
•Three tautomers of 5-methylbenzotriazole (5MeBTA) have similar stability.•Vibrational spectra show the presence of 1H- and 3H-5MeBTA tautomers in the solid state.•Formation of NH···N hydrogen bonds ...between the 1H- and 3H-5MeBTA tautomers is confirmed.•5MeBTA is a strong agent against A. niger, C. albicans and L. monocytogenes.
Three tautomeric forms (1H-, 2H-, 3H-) of 5-methylbenzotriazole (5MeBTA) and the tetramer, which includes the 1H-5MeBTA and 3H-5MeBTA tautomers connected by N3−H⋅⋅⋅N3 and N1−H⋅⋅⋅N2 intermolecular hydrogen bonds, have been studied by density functional theory (DFT) using B3LYP, B3LYP-D3 and ωB97XD methods combined with the 6–31++G(d,p) basis set. Calculations for the tetramer have revealed that intermolecular N3⋅⋅⋅N3 distances range from 2.881 to 2.851 Å, while the N1⋅⋅⋅N2 distances vary between 2.965 and 2.915 Å. These distances are very similar to those reported for the crystal of 5MeBTA (R. K. Belter, F. R. Fronczek, CCDC 1971683, 2019). The theoretical Raman and infrared spectra of the tetramer are in a very good agreement with the FT-Raman and FT-IR spectra of 5MeBTA in the solid state, measured in this work. A detailed interpretation of the experimental vibrational spectra has been made on the basis of the calculated potential energy distribution (PED). Microbiological studies in vitro were conducted for 5MeBTA and benzotriazole (BTA) against six bacterial strains (E. coli, K. pneumoniae, P. aeruginosa, B. subtilis, L. monocytogenes and S. aureus) and two fungal strains (A. niger and C. albicans). The results have shown that the substitution by the methyl group at the C-5 atom of BTA leads to an increase in activity against tested strains, in comparison to BTA. For 5MeBTA, the inhibition zones for bacteria and fungi range from 12 mm to 20 mm, and from 13 mm to 24 mm, respectively. The title compound has revealed particularly strong activity against A. niger, C. albicans and L. monocytogenes (with inhibition zones ≥ 20 mm).
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This study presents a new 5-methoxy-1
-indole-2-carboxylic acid (MI2CA) polymorph investigated by single-crystal X-ray diffraction, infrared spectroscopy, and density functional theory (ωB97X-D) ...calculations employing two basis sets (6-31++G(d,p) and aug-cc-pVTZ). The compound crystallizes in the monoclinic system, space group P2
/c (a = 4.0305(2) Å, b = 13.0346(6) Å, c = 17.2042(9) Å, β = 91.871(5)°, Z = 4). In the crystalline structure, the formation of cyclic dimers via double hydrogen bonds O-H⋯O between MI2CA molecules was observed. Interactions between the NH groups of the indole rings and the adjacent methoxy groups, as well as C-H⋯O contacts, significantly influence the spatial arrangement of molecules. The results from DFT calculations, including dimeric and trimeric structures, agree well with the experimental structural and spectroscopic data. Analysis of the infrared spectra confirms the conclusions drawn from X-ray diffraction studies and reveals differences between the IR spectra of the newly obtained polymorph and that reported earlier in the literature. This comprehensive study sheds some light on the MI2CA polymorphism and is important for a potential pharmacological applications of this compound.
Molecular structures of 5-chloro-7-azaindole-3-carbaldehyde (5Cl7AICA) and 4-chloro-7-azaindole-3-carbaldehyde (4Cl7AICA) were investigated using infrared and Raman spectroscopy supported by density ...functional theory (DFT) calculations. Theoretical studies were carried out with three DFT methods, which include dispersion corrections: B3LYP-D3, PBE0-D3, and ωB97X-D. A single-crystal X-ray diffraction analysis was performed for 5Cl7AICA. The compound crystallizes in the monoclinic system, space group P21/c, with lattice parameters a = 3.82810(12) Å, b = 12.7330(3) Å, c = 15.9167(5) Å, and β = 94.539(3)°, with Z = 4. Within the crystal lattice, 5Cl7AICA molecules form dimers via dual and strong N1–H1⋅⋅⋅N7′ hydrogen bonds, accompanied by other intermolecular interactions. In the DFT calculations, two types of dimers of the investigated molecules were analyzed: dimer 1, which is present in the crystal structure of 5Cl7AICA, and dimer 2 displaying a 180° rotation of the aldehyde group compared to dimer 1. Computational results indicate that dimer 1 is more stable than dimer 2 for 5Cl7AICA, whereas dimer 2 is more stable than dimer 1 for 4Cl7AICA molecules. Furthermore, experimental and theoretical vibrational spectra were examined to elucidate the influence of internal rotation of the aldehyde group on spectroscopic properties.
•Structures and vibrational spectra of 5-halo-1H-indole-2-carboxylic acids are studied.•Dimers with dual linear O−H⋅⋅⋅O hydrogen bonds are present in crystal of 5FI2CAH2.•IR and Raman spectra confirm ...the formation of the O−H⋅⋅⋅O dimers in the solid state.•B3LYP and MP2 calculations show that O−H⋅⋅⋅O dimers are the most stable.•5-halo-1H-indole-2-carboxylic acids are strong agents against L. monocytogenes.
Molecular structures and vibrational spectra of 5-fluoro-1H-indole-2-carboxylic acid (5FI2CAH2), 5‑chloro-1H-indole-2-carboxylic acid (5ClI2CAH2) and 5‑bromo-1H-indole-2-carboxylic acid (5BrI2CAH2) have been investigated. Single crystal X-ray diffraction for 5FI2CAH2 has revealed that a pair of 5FI2CAH2 molecules forms a cyclic dimer connected by dual linear O−H⋯O hydrogen bonds, while the NH group of the pyrrole ring does not participate in hydrogen bond. Theoretical studies were performed for the four possible dimers of 5XI2CAH2 (X = F, Cl, Br) using the B3LYP and MP2 methods with the 6–31++G(d,p) basis set. The calculated dimers included various possible combinations of O−H⋯O and N−H⋯O intermolecular interactions. The optimized structural parameters and the calculated vibrational spectra of the studied compounds show a good agreement with the experiment. The in vitro antibacterial activity against Gram-negative (E. coli, K. pneumoniae and P. aeruginosa) and Gram-positive (B. subtilis, L. monocytogenes and S. aureus) bacteria and antifungal activity against A. niger and C. albicans of 5XI2CAH2 have been investigated. All 5XI2CAH2 molecules have revealed particularly high activity against L. monocytogenes which is one of the most common of foodborne pathogens.
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In the present work seven new complexes of Pd(II) containing halogeno-derivatives of 7-azaindole (7AIH), PdCl2(L)2, where L = 3-chloro-7-azaindole (3Cl7AIH) or 3-bromo-7-azaindole (3Br7AIH) or ...4-chloro-7-azaindole (4Cl7AIH) or 4-bromo-7-azaindole (4Br7AIH) or 5-bromo-7-azaindole (5Br7AIH) or 3-bromo-4-chloro-7-azaindole (3Br4Cl7AIH) or 5-bromo-3-chloro-7-azaindole (5Br3Cl7AIH) were prepared and studied by infrared and Raman spectroscopy accompanied by the DFT calculations. Full geometry optimizations and vibrational frequency calculations were performed for the two possible isomers cis and trans of PdCl2(L)2 using the B3LYP method with the 6–311++G(d,p)/LanL2DZ basis sets. According to the theoretical results, the trans isomers are more stable than cis. As shown by the combined experimental and theoretical vibrational spectroscopic studies, only trans isomers with Ci symmetry are present, in the solid state. The combined experimental and theoretical studies have revealed that in PdCl2(L)2 complexes, palladium(II) is bound to two pyridine nitrogen atoms of L ligands and to two chloride ions, in a square-planar trans arrangement. Detailed vibrational assignments of the experimental infrared and Raman spectra of these complexes have been made on the basis of the calculated potential energy distributions (PEDs). The antiproliferative activity of selected trans-PdCl2(L)2 have been tested against human cancer cell lines (T47D, MCF7, A549 and A2780). The obtained IC50 values indicate that the title complexes possess lower cytotoxicity, in comparison to cisplatin.
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•Pd(II) complexes of seven halogeno-7-azaindole were synthesized.•The trans structures were confirmed by FT-IR, FT-Raman and DFT studies.•In trans-PdCl2(L)2, palladium is bonded to two Cl and two pyridine N atoms.•A detailed interpretation of the IR and Raman spectra is reported.•The trans-PdCl2(L)2 possess low cytotoxicity against the human cancer cell lines.
•The crystal structure of 1H-indazole-3-carbaldehyde (1) was analyzed in detail.•Two independent molecules of 1 are linked by the N−H⋅⋅⋅O hydrogen bonds.•The π⋅⋅⋅π, C=O⋅⋅⋅π and C−H⋅⋅⋅N interactions ...play an important role in crystal packing of 1.•Hirshfeld surface, NBO analysis, IR and Raman spectra confirm intermolecular interactions.
The title compound, 1H-indazole-3-carbaldehyde, C8H6N2O (1) is important as it represents a rare example of indazole found in nature. The asymmetric unit of 1 consists of two independent molecules (1A and 1B) which are linked by N—H⋅⋅⋅O hydrogen bonds (N⋅⋅⋅O = 2.8178(15) Å and 2.8203(14) Å), forming one-dimensional chains. The crystal structure is stabilized by slipped face-to-face π⋅⋅⋅π interactions (Cg⋅⋅⋅Cg distances in the range 3.8492(8) – 4.1830(8) Å), C=O⋅⋅⋅π interactions (O⋅⋅⋅centroids distances in the range 3.3252(12) – 3.4795(11) Å) and weak non-classical C—H⋅⋅⋅N hydrogen bonds (C⋅⋅⋅N = 3.4377(18) Å). 3D Hirshfeld surface analysis, 2D fingerprint plots and molecular electrostatic potentials were applied for a detailed investigation of all the interactions participating in the crystal packing. The intermolecular interactions were also confirmed by Natural Bond Orbital (NBO) analysis at the B3LYP and B3LYP-D3 levels using the 6-31++G(d,p) basis set. The energies of the intermolecular interactions (the second-order interaction energies, E2) oscillate between 55.5 kJ⋅mol−1 and 22.3 kJ⋅mol−1 for strong N−H⋅⋅⋅O hydrogen bond. The E2 value for the C=O⋅⋅⋅π and π⋅⋅⋅π interactions are about 4.9 kJ⋅mol−1 and 3.6 kJ⋅mol−1, respectively. Moreover, the strength of the hydrogen bonds was evaluated using vibrational spectroscopy (FT-IR and FT-Raman) and DFT calculations at the B3LYP level within the 6-31++G(d,p) basis set. These studies additionally confirm the presence of various intermolecular interactions in the crystal of 1.
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Structures and vibrational spectra of 3-bromo-7-azaindole (3Br7AI), 4-bromo-7-azaindole (4Br7AI), 4-chloro-7-azaindole (4Cl7AI), 5-bromo-3-chloro-7-azaindole (5Br3Cl7AI) and ...3-bromo-4-chloro-7-azaindole (3Br4Cl7AI) have been investigated. For the first time a single crystal analysis is reported for the three compounds: 3Br7AI (P21/n space group; a = 12.6586(3), b = 3.98664(12), c = 14.1189(4)Å, β = 100.901(2)o, Z = 4); 4Br7AI (P21/n space group; a = 5.38136 (13), b = 9.2262 (2), c = 13.9806 (4)Å, β = 90.052 (2)o, Z = 4); and 5Br3Cl7AI (C2/c space group; a = 22.9444(10), b = 3.91953(12), c = 17.8500(6)Å, β = 102.621(4)o, Z = 8). In the crystal structure, a pair of molecules forms a centrosymmetric dimer connected by dual nearly linear NH⋯N hydrogen bonds between the pyrrole and pyridine rings. In addition, the structures of 4Br7AI and 5Br3Cl7AI are stabilized by C2H2⋯Br hydrogen bonds. The IR and Raman spectra of all compounds and their N-deuterated derivatives were recorded in the solid state. The theoretical molecular structures and vibrational spectra of the centrosymmetric dimers of five investigated compounds were calculated using the B3LYP method with the 6-311G++(d,p) basis set. The optimized structural parameters and the calculated vibrational spectra reproduce well the experiment. Detailed vibrational assignments for all these compounds have been made on the basis of the calculated potential energy distributions (PEDs). The characteristic marker bands for the chloro- and bromo-derivativeds of 7-azaindoles are reported.
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•Halogeno-7-azaindoles in crystals form dimers with dual linear NH⋅⋅⋅N hydrogen bonds.•FT-Raman and FT-IR spectra are presented along with their detailed assignment.•Geometries and spectra calculated for dimers show very good agreement with experiment.•A complicated absorption from 3300 to 2500 cm−1 is due to multiple Fermi resonances.
Two Pd(II) complexes of 7-azaindole-3-carboxaldehyde (7AI3CAH) were synthesized. Structure of Pd2(7AI3CA)4 was confirmed by XRD, IR, Raman and DFT studies. In trans-PdCl2(7AI3CAH)2, palladium is ...bonded to two Cl and two pyridine N atoms. A detailed interpretation of the IR and Raman spectra is reported. trans-PdCl2(7AI3CAH)2 revealed remarkable cytotoxicity against T47D cancer cell lines.
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New Pd(II) complex, trans-PdCl2(7AI3CAH)2, containing 7-azaindole-3-carboxaldehyde (7AI3CAH) and the dinuclear complex Pd2(7AI3CA)4·DMSO with the deprotonated ligand (7AI3CA) have been prepared and characterized by X-ray crystallography, infrared and Raman spectroscopy, DFT calculations and antiproliferative activity studies. A single crystal X-ray analysis of Pd2(7AI3CA)4·DMSO has shown that the complex crystallizes in Cmca space group with the following unit cell dimensions: a = 15.6593(9), b = 17.9444(8), c = 13.8915(7) Å, V = 3903.5(3) Å3, Z = 4. Two ligands and DMSO solvate molecule are disordered. In this complex, the Pd24+ unit is surrounded by four N-deprotonated 7AI3CA− anions with a Pd–Pd distance of 2.7122(12) Å. Vibrational spectroscopic studies have revealed that in trans-PdCl2(7AI3CAH)2 complex, palladium(II) is bound to two pyridine nitrogen atoms of 7AI3CAH and to two chloride ions, in a square-planar trans arrangement. Comprehensive DFT calculations (including geometry optimizations, theoretical vibrational spectra and HOMO/LUMO orbitals) were performed for the four possible isomers of the dinuclear complex Pd2(7AI3CA)4 and for two isomers of PdCl2(7AI3CAH)2 using the B3LYP method with the 6–311++G(d,p)/LanL2DZ basis sets. The results have shown that the most stable isomers are: cis-(2,2)-Pd2(7AI3CA)4 for the dinuclear complex and trans-PdCl2(7AI3CAH)2 for the mononuclear complex. Detailed vibrational assignments of the experimental infrared and Raman spectra of both the palladium(II) complexes have been made on the basis of the calculated potential energy distributions (PEDs). The antiproliferative activity of trans-PdCl2(7AI3CAH)2 has been tested against the following human cancer cell lines: T47D and MCF7 (breast cancer), A549 (lung carcinoma), A2780 (ovarian cancer) and one normal cell line BALB/3T3 (mouse fibroblast). The trans-PdCl2(7AI3CAH)2 has revealed a remarkable cytotoxicity against the T47D tumour cell line (IC50 = 4.77 ± 1.61 μM), which is over three-times higher than the clinically used cisplatin (IC50 = 16.3 ± 3.9 μM). A study on stability of trans-PdCl2(7AI3CAH)2 in DMSO solution has been performed by FT-IR (ATR) spectroscopy.
