The crystal structures of fourN-(4-halophenyl)-4-oxo-4H-chromene-3-carboxamides

Four N-(4-halophen­yl)-4-oxo-4H-chromene-3-carboxamides (halo = F, Cl, Br and I), N-(4-fluoro­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10FNO3, N-(4-chloro­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10ClNO3, N-(4-bromo­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, N-(4-iodo­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10INO3, have been structurally characterized. The mol­ecules are essentially planar and each exhibits an anti conformation with respect to the C—N rotamer of the amide and a cis geometry with respect to the relative positions of the Carom—Carom bond of the chromone ring and the carbonyl group of the amide. The structures each exhibit an intra­molecular hydrogen-bonding network comprising an N—H⋯O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming an S(6) ring, and a weak Carom—H⋯O inter­action with the O atom of the carbonyl group of the amide as acceptor, which forms another S(6) ring. All four compounds have the same supra­molecular structure, consisting of R 2 2(13) rings that are propagated along the a-axis direction by unit translation. There is π–π stacking involving inversion-related mol­ecules in each structure.info:eu-repo/semantics/publishedVersio

Crystal structures of two 6-(2-hydroxybenzoyl)-5H-thiazolo[3,2-a]pyrimidin-5-ones

he title compounds, 6-(2-hy­droxy­benz­yl)-5H-thia­zolo[3,2-a]pyrimidin-5-one, C13H8N2O3S, (1), and 6-(2-hy­droxy­benz­yl)-3-methyl-5H-thia­zolo[3,2-a]pyrimidin-5-one, C14H10N2O3S, (2), were synthesized when a chromone-3-carb­oxy­lic acid, activated with (benzotriazol-1-yl­oxy)tripyrrolidinyl­phospho­nium hexa­fluorido­phosphate (PyBOP), was reacted with a primary heteromamine. Instead of the expected amidation, the unusual title thia­zolo­pyrimidine-5-one derivatives were obtained serendipitously and a mechanism of formation is proposed. Both compounds present an intra­molecular O-H...O hydrogen bond, which generates an S(6) ring. The dihedral angles between the heterocyclic moiety and the 2-hydroxybenzoyl ring are 55.22 (5) and 46.83 (6)° for (1) and (2), respectively. In the crystals, the mol­ecules are linked by weak C-H...O hydrogen bonds and [pi]-[pi] stacking inter­actions.info:eu-repo/semantics/publishedVersio

Crystal structures of three 3,4,5-trimethoxybenzamide-based derivatives

The crystal structures of three benzamide derivatives, viz. N-(6-hy-droxy-hex-yl)-3,4,5-tri-meth-oxy-benzamide, C16H25NO5, (1), N-(6-anilinohex-yl)-3,4,5-tri-meth-oxy-benzamide, C22H30N2O4, (2), and N-(6,6-di-eth-oxy-hex-yl)-3,4,5-tri-meth-oxy-benzamide, C20H33NO6, (3), are described. These compounds differ only in the substituent at the end of the hexyl chain and the nature of these substituents determines the differences in hydrogen bonding between the mol-ecules. In each mol-ecule, the m-meth-oxy substituents are virtually coplanar with the benzyl ring, while the p-meth-oxy substituent is almost perpendicular. The carbonyl O atom of the amide rotamer is trans related with the amidic H atom. In each structure, the benzamide N-H donor group and O acceptor atoms link the mol-ecules into C(4) chains. In 1, a terminal -OH group links the mol-ecules into a C(3) chain and the combined effect of the C(4) and C(3) chains is a ribbon made up of screw related R 2 (2)(17) rings in which the ⋯O-H⋯ chain lies in the centre of the ribbon and the tri-meth-oxy-benzyl groups forms the edges. In 2, the combination of the benzamide C(4) chain and the hydrogen bond formed by the terminal N-H group to an O atom of the 4-meth-oxy group link the mol-ecules into a chain of R 2 (2)(17) rings. In 3, the mol-ecules are linked only by C(4) chains.info:eu-repo/semantics/publishedVersio

Microencapsulation of herbicide MCPA with native β-cyclodextrin and its methyl and hydroxypropyl derivatives : an experimental and theoretical investigation

When a pesticide is released into the environment, most of it is lost before it reaches its target. An effective way to reduce environmental losses of pesticides is by using controlled release technology. Microencapsulation becomes a promising technique for the production of controlled release agricultural formulations. In this work, the microencapsulation of chlorophenoxy herbicide MCPA with native β-cyclodextrin and its methyl and hydroxypropyl derivatives was investigated. The phase solubility study showed that both native and β-CD derivatives increased the water solubility of the herbicide and inclusion complexes are formed in a stoichiometric ratio of 1:1. The stability constants describing the extent of formation of the complexes have been determined by phase solubility studies. 1H NMR experiments were also accomplished for the prepared solid systems and the data gathered confirm the formation of the inclusion complexes. 1H NMR data obtained for the MCPA/CDs complexes disclosed noticeable proton shift displacements for OCH2 group and H6 aromatic proton of MCPA provided clear evidence of inclusion complexation process, suggesting that the phenyl moiety of the herbicide was included in the hydrophobic cavity of CDs. Free energy molecular mechanics calculations confirm all these findings. The gathered results can be regarded as an essential step to the development of controlled release agricultural formulations containing herbicide MCPA.Fundação para a Ciência e a Tecnologia (FCT

New insights in the discovery of novelh-MAO-B inhibitors: structural characterization of a series ofN-phenyl-4-oxo-4H-chromene-3-carboxamide derivatives

Six N-substituted-phenyl 4-oxo-4H-chromene-3-carboxamides, namely N-(2-nitro­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10N2O5 (2b), N-(3-meth­oxy­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (3a), N-(3-bromo­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, (3b), N-(4-methoxy­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (4a), N-(4-methyl­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO3, (4d), and N-(4-hy­droxy­phen­yl)-4-oxo-4H-chromene-3-carboxamide, C16H11NO4, (4e), have been structurally characterized. All compounds exhibit an anti conformation with respect to the C—N rotamer of the amide and a trans-related conformation with the carbonyl groups of the chromone ring of the amide. These structures present an intra­molecular hydrogen-bonded network comprising an N—H⋯O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming an S(6) ring, and a weak Car—H⋯O hydrogen bond in which the carbonyl group of the amide acts as acceptor for the H atom of an ortho-C atom of the exocyclic phenyl ring, which results in another S(6) ring. The N—H⋯O intra­molecular hydrogen bond constrains the carboxamide moiety such that it is virtually coplanar with the chromone ring.info:eu-repo/semantics/publishedVersio

A comparison of the structures of some 2- and 3-substituted chromone derivatives: a structural study on the importance of the secondary carboxamide backbone for the inhibitory activity of MAO-B

The crystal structures of the 3-substituted tertiary chromone carboxamide derivative, C17H13NO3, N-methyl-4-oxo-N-phenyl-4H-chromene-3-carboxamide (1), and the chromone carbonyl pyrrolidine derivatives, C14H13NO3, 3-(pyrrolidine-1-carbon­yl)-4H-chromen-4-one (3) and 2-(pyrrolidine-1-carbon­yl)-4H-chromen-4-one (4) have been determined. Their structural features are discussed and compared with similar compounds namely with respect to their MAO-B inhibitory activities. The chromone carboxamide presents a -syn conformation with the aromatic rings twisted with respect to each other [the dihedral angle between the mean planes of the chromone system and the exocyclic phenyl ring is 58.48 (8)°]. The pyrrolidine derivatives also display a significant twist: the dihedral angles between the chromone system and the best plane formed by the pyrrolidine atoms are 48.9 (2) and 23.97 (12)° in (3) and (4), respectively. Compound (3) shows a short C-H...O intra­molecular contact forming an S(7) ring. The supra­molecular structures for each compound are defined by weak C-H...O hydrogen bonds, which link the mol­ecules into chains and sheets. The Cambridge Structural Database gave 45 hits for compounds with a pyrrolidinecarbonyl group. A simple statistical analysis of their geometric parameters is made in order to compare them with those of the mol­ecules determined in the present work.info:eu-repo/semantics/publishedVersio

Biofilm control by ionic liquids

Ionic liquids (ILs) are remarkable chemical compounds with applications in many areas of modern science. They are increasingly recognized as promising compounds to fight microorganisms in both planktonic and biofilm states, contributing to reinvent the antimicrobial pipeline. Biofilm-related infections are particularly challenging given that the scientific community has not yet identified a reliable control strategy. Understanding of the action of ILs in biofilm control is lacking. However, given the highly tunable nature and exceptional properties of ILs, they are excellent candidates for biofilm control. Here, we review the major advances in, and challenges to, the use of ILs for effective biofilm control.Base Funding - UIDB/00511/2020 of LEPABE, UIDB/00081/2020 of CIQUP, and UIDB/04469/2020 of CEB funded by national funds through the FCT/MCTES (PIDDAC); Project Biocide_for_Biofilm - PTDC/BII-BTI/30219/2017 - POCI-01-0145-FEDER-030219, ABFISH – PTDC/ASP-PES/28397/2017 - POCI-01-0145-FEDER-028397, funded by FEDER funds through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES, and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norteinfo:eu-repo/semantics/publishedVersio

Crystal structures of five 6-mercaptopurine derivatives

The crystal structures of five 6-mercaptopurine derivatives, viz. 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(3-meth-oxy-phen-yl)ethan-1-one (1), C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-meth-oxy-phen-yl)ethan-1-one (2), C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-chloro-phen-yl)ethan-1-one (3), C15H11ClN4O2S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-bromo-phen-yl)ethan-1-one (4), C15H11BrN4O2S, and 1-(3-meth-oxy-phen-yl)-2-[(9H-purin-6-yl)sulfan-yl]ethan-1-one (5), C14H12N4O2S. Compounds (2), (3) and (4) are isomorphous and accordingly their mol-ecular and supra-molecular structures are similar. An analysis of the dihedral angles between the purine and exocyclic phenyl rings show that the mol-ecules of (1) and (5) are essentially planar but that in the case of the three isomorphous compounds (2), (3) and (4), these rings are twisted by a dihedral angle of approximately 38°. With the exception of (1) all mol-ecules are linked by weak C-H⋯O hydrogen bonds in their crystals. There is π-π stacking in all compounds. A Cambridge Structural Database search revealed the existence of 11 deposited compounds containing the 1-phenyl-2-sulfanyl-ethanone scaffold; of these, only eight have a cyclic ring as substituent, the majority of these being heterocycles.info:eu-repo/semantics/publishedVersio

Electrochemical sensing of the thyroid hormone thyronamine (T0AM) via molecular imprinted polymers (MIPs)

Recent studies have shown that besides the well-known T3 (triiodothyronine) and T4 (thyroxine) there might be other important thyroid hormones, in particular T0AM (thyronamine) and T1AM (3-iodothyronamine). The absence of a large number of studies showing their precise importance might be explained by the limited number of analytical methodologies available. This work aims to show an electroanalytical alternative making use of electropolymerized molecularly imprinted polymer (MIPs). The MIPs' polymerization is performed on the surface of screen-printed carbon electrodes (SPCEs), using 4-aminobenzoic acid (4-ABA) as the building and functional monomer and the analyte T0AM as the template. The step-by-step construction of the SPCE-MIP sensor was studied by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS). After optimization, by means of square-wave voltammetry, the SPCE-MIP showed suitable selectivity (in comparison with other thyroid hormones and catechol amines), repeatability (intra-day of 3.9%), a linear range up to 10 μmol L-1 (0.23 × 103 μg dL-1) with an r2 of 0.998 and a limit of detection (LOD) and quantification (LOQ) of 0.081 and 0.27 μmol L-1 (1.9 and 6.2 μg dL-1), respectively.This project was supported by Fundação para a Ciência e a Tecnologia (FCT), and FEDER/COMPETE (UID/QUI/00081/2013, UID/QUI/50006/2013, POCI-01-0145-FEDER-006980 and NORTE-01-0145-FEDER-000028). JGP (SFRH/BPD/101419/2014), PR (SFRH/BD/132384/2017) and LMG (SFRH/BPD/76544/2011) wish to acknowledge FCT for their research grants. FC thanks NORTE-01-0145-FEDER-000028 grant.info:eu-repo/semantics/publishedVersio

Host-guest complexes of phenoxy alkyl acid herbicides and cyclodextrins. MCPA and β-cyclodextrin

The chlorophenoxy herbicideMCPA(4-chloro-2-methylphenoxyacetic acid), widely used for the control of broad-leafweeds primarily in cereal and grass seed crops, still remains one of the most often used herbicides in Portugal. As the formation of inclusion complexes with cyclodextrins can improve its solubility properties, the interaction between the herbicide MCPA and β-cyclodextrin was investigated. The stability constants describing the extent of formation of the complexes have been determined by phase-solubility studies. Different analytical techniques [ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR)] were employed for a thorough investigation of the structural characteristics of the obtained complexes, which exhibited distinct features and properties from both “guest” and “host” molecules. FTIR and 1H NMR data obtained for the MCPA/β-CD complexes gave information about the interaction between MCPA and the nonpolar cyclodextrin cavity. The dramatic change observed in band frequency and proton displacements of OCH2 group and H6 aromatic proton confirmed the inclusion of MCPA in β-CD. The formation of an inclusion complex between MCPA and β-CD increased the aqueous solubility of this herbicide which could be a particularly advantageous property for some specific applications, namely to improve commercial formulation and for environmental protection.info:eu-repo/semantics/publishedVersio