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  • 1
    Online Resource
    Online Resource
    POLY(VINYLPYRROLIDONE)-CHITOSAN HYDROGELS AS MATRICES FOR CONTROLLED DRUG RELEASE
    Institutul de Chimie Macromoleculara Petru Poni ; 2021
    In:  Cellulose Chemistry and Technology Vol. 55, No. 1-2 ( 2021-2-12), p. 63-73
    Details
    In: Cellulose Chemistry and Technology, Institutul de Chimie Macromoleculara Petru Poni, Vol. 55, No. 1-2 ( 2021-2-12), p. 63-73
    Abstract: In this study, hydrogels based on poly(vinylpyrrolidone) and chitosan, derived from different mixing ratios of poly(vinylpyrrolidone)/chitosan, were synthesized by the freeze-drying technique with the aim of obtaining new systems that could be used to release tetracycline hydrochloride (TH). Freeze-drying methods were also used to prepare the hydrogels containing TH. The hydrogels were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy, as well as in terms of dynamic water vapour sorption capacity. The poly(vinylpyrrolidone)/chitosan hydrogels were evaluated with regard to the release of TH. The release profiles of TH from the poly(vinylpyrrolidone)/chitosan hydrogels depended on the chitosan content. It could be seen that if the concentration of chitosan was too high, the release was delayed and not fully achieved, because the release of the drug was prevented by the crystalline areas of the chitosan. According to the release study, the drug release mechanism of the poly(vinylpyrrolidone)/chitosan hydrogels loaded with TH perfectly fitted the Higuchi and the Korsmeyer-Peppas models. The highest value of water vapor sorption capacity was obtained for the hydrogel with the poly(vinylpyrrolidone)/chitosan ratio of 50/50. PVP-CS loaded with 3 wt% TH may potentially be used for the controlled delivery of tetracycline to treat oral infections.
    Type of Medium: Online Resource
    ISSN: 0576-9787 , 2457-9459
    URL: Issue
    URL: Journal
    URL: Article
    DOI: 10.35812/CelluloseChemTechnol.2021.55
    DOI: 10.35812/CelluloseChemTechnol
    DOI: 10.35812/CelluloseChemTechnol.2021.55.07
    Language: Unknown
    Publisher: Institutul de Chimie Macromoleculara Petru Poni
    Publication Date: 2021
    detail.hit.zdb_id: 2786413-3
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  • 2
    Online Resource
    Online Resource
    Synthesis and crystal structure of N 1 , N 2 -dimethylethanedihydrazide
    International Union of Crystallography (IUCr) ; 2024
    In:  Acta Crystallographica Section E Crystallographic Communications Vol. 80, No. 2 ( 2024-02-01)
    Details
    In: Acta Crystallographica Section E Crystallographic Communications, International Union of Crystallography (IUCr), Vol. 80, No. 2 ( 2024-02-01)
    Abstract: The title compound, N 1 , N 2 -dimethylethanedihydrazide, C 4 H 10 N 4 O 2 , was obtained by the methylation of oxalyl dihydrazide protected with phthalimide. The molecule is essentially non-planar with a dihedral angle between the two planar hydrazide fragments of 86.5 (2)°. This geometry contributes to the formation of a multi-contact three-dimensional supramolecular network via C—H...O, N—H...O and N—H...N hydrogen bonds.
    Type of Medium: Online Resource
    ISSN: 2056-9890
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1107/S2056989024000239
    DOI: 10.1107/S2056989024000239/vm2294sup1.cif
    DOI: 10.1107/S2056989024000239/vm2294Isup4.hkl
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2024
    detail.hit.zdb_id: 2843762-7
    detail.hit.zdb_id: 2041947-8
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  • 3
    Online Resource
    Online Resource
    Synthesis and crystal structure of a cadmium(II) coordination polymer based on 4,4′-(1 H -1,2,4-triazole-3,5-diyl)dibenzoate
    International Union of Crystallography (IUCr) ; 2024
    In:  Acta Crystallographica Section E Crystallographic Communications Vol. 80, No. 2 ( 2024-02-01)
    Details
    In: Acta Crystallographica Section E Crystallographic Communications, International Union of Crystallography (IUCr), Vol. 80, No. 2 ( 2024-02-01)
    Abstract: The asymmetric unit of the title compound, catena -poly[[[aquabis(pyridine-κ N )cadmium(II)]-μ 2 -4,4′-(1 H -1,2,4-triazole-3,5-diyl)dibenzoato-κ 4 O , O ′: O ′′, O ′′′] 4.5-hydrate] , {[Cd(C 16 H 9 N 3 O 4 )(C 5 H 5 N) 2 (H 2 O)]·4.5H 2 O} n or {[Cd(bct)(py) 2 (H 2 O)]·4.5H 2 O} n ( I ), consists of a Cd 2+ cation coordinated to one bct 2– carboxylate dianion, two molecules of pyridine and a water molecule as well as four and a half water molecules of crystallization. The metal ion in I possesses a pentagonal–bipyramidal environment with the four O atoms of the two bidentately coordinated carboxylate groups and the N atom of a pyridine molecule forming the O 4 N equatorial plane, while the N atom of another pyridine ligand and the O atom of the water molecule occupy the axial positions. The bct 2– bridging ligand connects two metal ions via its carboxylic groups, resulting in the formation of a parallel linear polymeric chain running along the [1\overline{1}1] direction. The coordinated water molecule of one chain forms a strong O—H...O hydrogen bond with the carboxylate O atom of a neighboring chain, leading to the formation of double chains with a closest distance of 5.425 (7) Å between the cadmium ions belonging to different chains. Aromatic π–π stacking interactions between the benzene fragments of the anions as well as between the coordinated pyridine molecules belonging to different chains results in the formation of sheets oriented parallel to the (\overline{1}01) plane. As a result of hydrogen-bonding interactions involving the water molecules of crystallization, the sheets are joined together in a three-dimensional network.
    Type of Medium: Online Resource
    ISSN: 2056-9890
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1107/S2056989024000185
    DOI: 10.1107/S2056989024000185/hb8090sup1.cif
    DOI: 10.1107/S2056989024000185/hb8090Isup2.hkl
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2024
    detail.hit.zdb_id: 2843762-7
    detail.hit.zdb_id: 2041947-8
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  • 4
    Online Resource
    Online Resource
    Crystal structure of bis{2-[5-(3,4,5-trimethoxyphenyl)-4 H -1,2,4-triazol-3-yl]pyridine}palladium(II) bis(trifluoroacetate) trifluoroacetic acid disolvate
    International Union of Crystallography (IUCr) ; 2024
    In:  Acta Crystallographica Section E Crystallographic Communications Vol. 80, No. 6 ( 2024-06-01), p. 567-571
    Details
    In: Acta Crystallographica Section E Crystallographic Communications, International Union of Crystallography (IUCr), Vol. 80, No. 6 ( 2024-06-01), p. 567-571
    Abstract: The new palladium(II) complex, [Pd(C 16 H 16 N 4 O 3 ) 2 ](CF 3 COO) 2 ·2CF 3 COOH, crystallizes in the triclinic space group P \overline{1} with the asymmetric unit containing half the cation (Pd II site symmetry C i ), one trifluoroactetate anion and one co-crystallized trifluoroacetic acid molecule. Two neutral chelating 2-[5-(3,4,5-trimethoxyphenyl)-4 H -1,2,4-triazol-3-yl]pyridine ligands coordinate to the Pd II ion through the triazole-N and pyridine-N atoms in a distorted trans -PdN 4 square-planar configuration [Pd—N 1.991 (2), 2.037 (2) Å; cis N—Pd—N 79.65 (8), 100.35 (8)°]. The complex cation is quite planar, except for the methoxo groups (δ = 0.117 Å for one of the C atoms). The planar configuration is supported by two intramolecular C—H...N hydrogen bonds. In the crystal, the π–π-stacked cations are arranged in sheets parallel to the ab plane that are flanked on both sides by the trifluoroacetic acid–trifluoroacetate anion pairs. Apart from classical N/O—H...O hydrogen-bonding interactions, weak C—H...F/N/O contacts consolidate the three-dimensional architecture. Both trifluoroacetic moieties were found to be disordered over two resolvable positions with a refined occupancy ratio of 0.587 (1):0.413 (17) and 0.530 (6):0.470 (6) for the protonated and deprotonated forms, respectively.
    Type of Medium: Online Resource
    ISSN: 2056-9890
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1107/S205698902400392X
    DOI: 10.1107/S205698902400392X/jw2005sup1.cif
    DOI: 10.1107/S205698902400392X/jw2005Isup2.hkl
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2024
    detail.hit.zdb_id: 2843762-7
    detail.hit.zdb_id: 2041947-8
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