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C19H20O4, monoclinic, P21/c (no. 14), a = 16.5979(5) Å, b = 8.5654(2) Å, c = 11.8418(4) Å, β = 108.537(4)°, V = 1596.18(8) Å3, Z = 4, Rgt(F) = 0.0385, wRref(F2) = 0.0973, T = 190 K.

The development of an appropriate delivery system of active pharmaceutical ingredients (APIs) is an absolute necessity in the treatment of different diseases. Recently, DESs have been intensively studied for the purpose of improved API delivery. As a part of our continuous investigations in this particular field, we have prepared and characterized two new deep eutectic solvents with pharmaceutically active ingredients. Lidocaine (Lid), 7-hydroxy-4-methylcoumarin (Cou) and lactic (La) or levulinic (Le) acid were used for the preparation of the desired DESs. Both solvents were characterized by different methods in order to determine their physical and chemical properties. The water content determined by Karl–Fischer titration is 1.02% and 1.66%, respectively, while the polarity of both solvents is between the polarity of water and methanol. NMR and IR studies indicate the presence of Cou in the deprotonated (anionic) form, Lid in both neutral and protonated forms, and acids in the neutral form. Spectroscopic studies indicate the presence of strong O–H⋯O and C–O⋯H hydrogen bonds in both DESs. In silico methods provided a deeper insight into the complex intermolecular interaction patterns between the components of the prepared deep eutectic solvents. The thermal analysis indicates that these solvents can be considered as DESs with high thermal stability. [ABSTRACT FROM AUTHOR]

Silver(I) complexes with aza-oxa macrocyclic Schiff bases L (L = 1,5-diaza-2,4:7,8:16,17-tribenzo-9,15-dioxa-cyclooctadeca-1,5-dien) were prepared by the reaction of the corresponding macrocycle with four different silver salts (AgX; X = ClO4, PF6, SbF6 and BF4). In all four compounds, silver ions are exo-coordinated by two neighboring ligand molecules in linear and T-shaped geometries. Such a coordination mode results in the formation of infinite 1D polymeric chains. Compounds AgLClO4 and AgLBF4 are isostructural, and polymeric chains display 1D zigzag topology. In AgLPF6 there are three symmetrically unique Ag ions in the asymmetric unit of the compound. Two silver ions are linearly coordinated with two neighboring ligand molecules and are part of a discrete polymer chain. The third silver ion is coordinated with two ligand molecules and a methanol molecule in a T-shaped geometry. Such coordination geometry results in the formation of two discrete infinite polymer chains in the crystal structure. In the AgLSbF6 compound, the chain topology is a linear zigzag chain, but in this compound, there is a difference in the orientation of the Ag-N bond. The Ag-N-Ag bonds are in the trans position relative to the plane calculated through the ligand molecule, while the Ag-N bonds are in the cis position in all other compounds. Due to the presence of a bulky SbF6 anion, the ligand molecule is planar compared to other compounds. Considering intermolecular interactions, there is a huge variety of different interactions, mostly depending on the type of anion. A general supramolecular motif in all compounds is best described as 2D sheets of ligand–metal polymers with anions and solvent molecules sandwiched between them. In addition, the obtained compounds were characterized by IR spectroscopy and thermal analysis. The TG analysis indicates a rather surprising and considerable thermal stability of the prepared compounds, with some compounds thermally stable over 300 °C. [ABSTRACT FROM AUTHOR]

The century-old, well-known odd–even effect phenomenon is still a very attractive and intriguing topic in supramolecular and nano-scale organic chemistry. As a part of our continuous efforts in the study of supramolecular chemistry, we have prepared three novel aromatic alcohols (1,2-bis[2-(hydroxymethyl)phenoxy]butylene (Do4OH), 1,2-bis[2-(hydroxymethyl)phenoxy]pentylene (Do5OH) and 1,2-bis[2-(hydroxymethyl)phenoxy]hexylene (Do6OH)) and determined their crystal and molecular structures by single-crystal X-ray diffraction. In all compounds, two benzyl alcohol groups are linked by an aliphatic chain of different lengths (CH2)n; n = 4, 5 and 6. The major differences in the molecular structures were found in the overall planarity of the molecules and the conformation of the aliphatic chain. Molecules with an even number of CH2 groups tend to be planar with an all-trans conformation of the aliphatic chain, while the odd-numbered molecule is non-planar, with partial gauche conformation. A direct consequence of these structural differences is visible in the melting points—odd-numbered compounds of a particular series display systematically lower melting points. Crystal and molecular structures were additionally studied by the theoretical calculations and the melting points were correlated with packing density and the number of CH2 groups. The results have shown that the generally accepted rule, higher density = higher stability = higher melting point, could not be applied to these compounds. It was found that the denser packaging causes an increase in the percentage of repulsive H‧‧‧H interactions, thereby reducing the stability of the crystal, and consequently, the melting points. Another interesting consequence of different molecular structures is their electrochemical and antioxidative properties—a non-planar structure displays the highest oxidation peak of hydroxyl groups and moderate antioxidant activity. [ABSTRACT FROM AUTHOR]

The reactions of picolinamide (pyridine-2-carboxamide, pia) with various cadmium(II) salts in aqueous media were investigated. With cadmium(II) halides, three novel coordination polymers (CPs) were isolated, namely: [CdX 2 (pia)] n (X = Cl ( 1 ), Br ( 2 ), I ( 3 ). Cadmium(II) sulphate gave [Cd(SO 4 )(pia)(H 2 O) 3 ] ·2H 2 O ( 4) while cadmium(II) nitrate in the presence of perchlorate ions gave mixed complex [Cd(pia) 3 (H 2 O)](NO 3 )(ClO 4 ) ( 5 ) with both anions acting as counterions. All isolated complexes were identified by chemical analysis and characterized using IR-spectroscopy and thermal methods (TG/DSC). X-ray crystal structure analysis of 1 – 3 revealed a distorted octahedral coordination of Cd(II) which consists of four halide and N,O- chelated pia ligands. The chain propagation is achieved through metal-halide double-bridges. The pia ligand is in cis geometry ( cis- configured polymeric chain) and the topology of chains can be described as zig-zag. In 1 the neighbouring chains are mutually linked through weak C H···Cl and N H···Cl hydrogen bonds into 3D supramolecular framework. In 2 and 3, which are isostructural, unlike in 1 the neighbouring chains are linked by a strong head-to-head amide hydrogen bonds (graph set R 2 2 (8)) into supramolecular sheets in (0 1 0) planes and through weak C H···X interactions a 3D supramolecular framework is accomplished. In discrete molecules of 4 and 5 , a distorted octahedral and pentagonal bipyramidal coordination of Cd(II) ion is revealed respectively. The final 3D supramolecular dimensionality of 4 and 5 is achieved through non-covalent interactions including sulphate ions in the former, and perchlorate and nitrate ions in the later thus pointing a discernible influence of anions on the structure. [ABSTRACT FROM AUTHOR]

C19H20O4, monoclinic, P21/c (no. 14), a=16.5979(5) Å, b=8.5654(2) Å, c=11.8418(4) Å, β=108.537(4)°, V=1596.18(8) ų, Z=4, Rgt(F)=0.0385, wRref(F²)=0.0973, T=190 K. [ABSTRACT FROM AUTHOR]

C19H20O4, monoclinic, P21/c (no. 14), a=16.5979(5) Å, b=8.5654(2) Å, c=11.8418(4) Å, β=108.537(4)°, V=1596.18(8) ų, Z=4, Rgt(F)=0.0385, wRref(F²)=0.0973, T=190 K. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel trinuclear iron(III) acetate as with uncoordinated hexamine. • The complex has been structurally characterized by single crystal X-ray diffraction. • The impact of hexamine on intermolecular interactions was studied. • High-spin iron ions in +3 oxidation state with non-Curie-like behaviour. • Antiferromagnetic interactions between the three individual Fe(III) ions. Structural characterization of novel Fe(III) basic acetate with 1,3,5,7-tetraazaadamantane (hexamine – HEX), [Fe 3 (μ 3 -O)(OAc) 6 (H 2 O) 3)](NO 3)(HEX) 2 (H 2 O) 5 (1), revealed a molecular structure typical for Fe(III) basic carboxylates, with a triangular array formed by three iron atoms being equilateral and with an uncoordinated hexamine molecule and nitrate anion present in the crystal structure. Despite the hexamine molecule being uncoordinated, it plays a crucial role in the formation of a supramolecular network. The magnetic properties of the compound were characterized by magnetic susceptibility, Mössbauer and EPR spectroscopy. These studies indicate the presence of high-spin iron ions in +3 oxidation state with non-Curie-like behaviour. A small room temperature value of the effective magnetic moment and a decrease of the product χT with decreasing temperature both speak in favour of antiferromagnetic interactions between the three individual Fe(III) ions of complex 1 with a total ground state spin of S t = 1/2 per trinuclear cluster. EPR spectroscopy confirmed the formation of a S t = 1/2 ground state, but also suggested the presence of weak intermolecular exchange interactions between two (or more) clusters of neighbouring molecules. The temperature-dependent Mössbauer spectra show a slowing-down of the fast spin-lattice relaxation rates of the paramagnetic Fe(III) ion below about 60 K, however, yet no static spin regime is reached down to 3.6 K. [ABSTRACT FROM AUTHOR]

Drug–drug cocrystals are formulated to produce combined medication, not just to modulate active pharmaceutical ingredient (API) properties. Nano-crystals adjust the pharmacokinetic properties and enhance the dissolution of APIs. Nano-cocrystals seem to enhance API properties by combining the benefits of both technologies. Despite the promising opportunities of nano-sized cocrystals, the research at the interface of nano-technology and cocrystals has, however, been described to be in its infancy. In this study, high-pressure homogenization (HPH) and high-power ultrasound were used to prepare nano-sized cocrystals of 4-aminosalysilic acid and sulfamethazine in order to establish differences between the two methods in terms of cocrystal size, morphology, polymorphic form, and dissolution rate enhancement. It was found that both methods resulted in the formation of form I cocrystals with a high degree of crystallinity. HPH yielded nano-sized cocrystals, while those prepared by high-power ultrasound were in the micro-size range. Furthermore, HPH produced smaller-size cocrystals with a narrow size distribution when a higher pressure was used. Cocrystals appeared to be needle-like when prepared by HPH compared to those prepared by high-power ultrasound, which had a different morphology. The highest dissolution enhancement was observed in cocrystals prepared by HPH; however, both micro- and nano-sized cocrystals enhanced the dissolution of sulfamethazine. [ABSTRACT FROM AUTHOR]

(i) Monosubstituted dipicolinic acid hydrazide derivative. (ii) N,N,O -tridentate ligand. Co(III) and Cr(III) complexes. (iii) Isostructural octahedral complexes with similar crystal packing. (iv) SC-XRD, TG/DSC, FTIR, NMR, CV analyses. A novel monosubstituted dipicolinic acid hydrazide derivative ( H 2 L = 6-{[2-(phenylcarbonyl)hydrazino]carbonyl}pyridine-2-carboxylic acid) was prepared by the multi-step synthesis route starting from methoxy-substituted pyridine-2,6-dicarboxylic acid. Reaction of the prepared compound with Co and Cr salts in the presence of 1,6-diaminohexane resulted in formation of discrete complex compounds ( CoL and CrL ). The synthesized compounds were identified by chemical analyses and characterized by IR spectroscopy, thermal analysis and the ligand additionally by NMR spectroscopy. The crystal and molecular structure of the prepared complexes were determined by the single-crystal X-ray diffraction and electrochemical properties by cyclic voltammetry. The molecular structure of the complex compounds is found to be isostructural with rather small differences in the crystal packing arrangement. In both complexes the coordination geometry is octahedral and each metal ion is coordinated by two mutually orthogonal ligand molecules that act as N , N , O -tridentate ligand. In the crystal structure, the molecules are linked via multiple O–H⋯O, N–H⋯O and N–H⋯Cl hydrogen bond interactions thus forming a supramolecular zig-zag motif that is additionally stabilized by a series of hydrogen bond interactions that involve water molecule, diaminohexane cation, uncoordinated oxygen atom of carboxylic group and oxygen atom of carbonyl group. Electrochemical analysis of complex compounds indicated irreversible oxidation of Cr3+ in CrL and reduction of Co3+ to Co2+ in CoL , which agrees with the proposed oxidation state of the metal in complexes. [ABSTRACT FROM AUTHOR]

The removal and detection of highly toxic and environmentally harmful gases such as SO 2 , H 2 S and CO 2 is a hot topic of the scientific community. Porous organic compounds, in particular, imine-based macrocycles, are promising materials for this purpose. In this paper we have used porous N 4 O 4 -donor macrocyclic Schiff base (1,6,20,25-tetraaza-2,5:8,9:17,18:21,24:27,28:36,37-hexabenzo-10,16,29,35-tetraoxa-cyclooctatriakonta-1,6,20,25-tetraen) (1) for sorption of NH 3 , SO 2 , Cl 2 , CO 2 and H 2 S. Five novel inclusion compounds 1xNH 3 , 1xSO 2 , 1xCl 2, 1xCO 2 and 1xH 2 S were prepared by a single-crystal to single-crystal (SC-SC) transformation. Single-crystal X-ray diffraction (SCXRD) analysis of 1xCO 2 and 1xNH 3 inclusion compounds have shown that CO 2 molecule resides in the plane of the macrocyclic ring connected by weak C–O ... π interactions to the host, and no host-guest interactions in 1xNH 3 were observed. The relative thermal stabilities of the host-guest systems (T on – T b parameter) is in the range from 93 (1xNH 3) to 132 °C (1xH 2 S), indicating the formation of stable inclusion compounds. Although used gases are highly reactive and corrosive, FT-IR and powder diffraction studies indicate that the molecular and crystal structure of the host is constant upon gas sorption. The activated compound displays moderate uptake (0.35 mmol/g) of CO 2 at 298 K. The relatively high thermal stability, constant molecular and crystal structure of inclusion compounds with interesting optical properties (determined by solid state UV–Vis) make this material potentially useful for the detection of toxic gases. Novel inclusion complexes of porous macrocyclic Schiff base (1,6,20,25-tetraaza-2,5:8,9:17,18:21,24:27,28:36,37-hexabenzo-10,16,29,35-tetraoxa-cyclooctatriakonta-1,6,20,25-tetraen) were prepared by single-crystal to single-crystal (SC-SC). Inclusion complexes with CO 2 , NH 3 , SO 2 , Cl 2 and H 2 S were prepared and characterized by thermal analysis, spectroscopy (NMR and FT-IR) and the single-crystal X-ray diffraction (SCXRD). [Display omitted] • CO 2 , NH 3 , SO 2 , Cl 2 and H 2 S inclusion compounds were prepared by single-crystal to single-crystal (SC-SC) transformation. • Crystal structures were determined for CO 2 (1xCO 2) and NH 3 (1xNH 3) inclusion compounds. • In 1xCO 2 , the CO 2 molecules form weak C–O ... π interactions to the host. • T on – T b parameter is 93 °C, 110 °C, 120 °C and 132 °C for 1xNH 3 , 1xSO 2 , 1xCl 2 and 1xH 2 S , respectively. • GCMC simulations indicate maximum absence of strong host-guest interactions. [ABSTRACT FROM AUTHOR]

Despite polymorphism of crystalline active pharmaceutical ingredients (APIs) being a common phenomenon, reports on polymorphic co-crystals are limited. As polymorphism can vastly affect API properties, controlling polymorph generation is crucial. Control of the polymorph nucleation through the use of different solvents during solution crystallization has been used to obtain a desirable crystal polymorph. There have been two reported polymorphic forms of the 4-aminosalicylic acid-sulfamethazine co-crystals. These forms were found to have different thermodynamic stabilities. However, the control of co-crystal polymorph generation using preparation parameter manipulation has never been reported. The aim of this study was to establish the effect of different solvent parameters on the formation of different co-crystal polymorphic forms. Selection of the solvents was based on Hansen Solubility Parameters (HSPs) as solvents with different solubility parameters are likely to interact differently with APIs, ultimately affecting co-crystallization. Eight solvents with different HSPs were used to prepare co-crystals by solvent evaporation at two different temperatures. Through characterization of the co-crystals, a new polymorph has been obtained. The hydrogen bond acceptability seemed to affect the co-crystal form obtained more than the hydrogen bond donation ability. Furthermore, the use of HSPs can be utilized as an easy calculation method in screening and design of co-crystals. Image, graphical abstract [ABSTRACT FROM AUTHOR]