Morphological and Structural Characterization of (Pt, Au, and Ag) Nanoparticle/Zn-MOF-74 Composites.

Metallic nanoparticles (NPs) were decorated onto Zn-MOF-74 crystals by photoreducing different metal precursors (Pt, Au, and Ag) using ultraviolet (UV) light in an aqueous solution with different metal concentrations without using additional stabilizers. X-ray diffraction revealed the three-dimensional structural integrity and crystallinity conservation of Zn-MOF-74 crystals during the UV decoration process. Raman spectroscopy showed a minor rearrangement in the structure of the Zn-MOF-74 crystal surface after NP decoration.

Hexamethylenetetramine-tridecanedioic acid (1/1): temperature-induced order-disorder structural phase transitions with phase co-existence.

The cocrystal hexamethylenetetramine-tridecanedioic acid (1/1) (HMT-C13), CHN·CHO, was investigated by single-crystal X-ray diffraction techniques at several temperatures during cooling and heating processes. Our results show the formation of two crystalline phases, separated by a large temperature phase co-existence between 290 and 340 K. Phase I, stable above 341 K, presents an orthorhombic structure described in the space group Bmmb, with one N(CH)·CHO adduct in its asymmetric unit.

Investigation of cobalt(iii)-triazole systems as prototypes for hypoxia-activated drug delivery.

Three novel cobalt(iii)-triazole complexes with structural and redox properties suitable for hypoxia-activated drug delivery were obtained. A major influence of the ancillary ligands (TPA, py2en, py2enMe2) on the electronic properties and reactivity of their complexes was observed. An [O2]-dependent reduction to cobalt(ii) by ascorbic acid provided evidence of hypoxic selectivity.

4α-Acetoxyamijidictyol - A New Antifeeding Dolastane Diterpene from the Brazilian Brown Alga Canistrocarpus cervicornis.

Chemical investigation of the CH2 Cl2 crude extract from the brown alga Canistrocarpus cervicornis (Dictyotaceae) led to isolation of one new (1) and four previously reported dolastane diterpenes (2-5). Their structures were characterized by 1D- and 2D-NMR spectroscopic techniques, including a full single crystal X-ray diffraction analysis for 1, 2, and 4. In addition, the new structure 1 was assayed as chemical defense inhibiting the feeding by the sea urchin Lytechinus variegatus.

Superspace crystallography: a key to the chemistry and properties.

An overview is given of the recent advances in the field of modulated molecular and inorganic crystals with an emphasis on the links between incommensurability, intermolecular and interatomic interactions and, wherever possible, the properties of the materials. The importance of detailed knowledge on the modulated structure for understanding the crystal chemistry and the functional properties of modulated phases is shown using selected examples of incommensurate modulations in organic molecular compounds and inorganic complex oxides.

The structure of the 1H-imidazol-3-ium lawsonate salt aided by ab initio gas-phase calculations.

For the new organic salt 1H-imidazol-3-ium 1,4-dioxo-1,4-dihydronaphthalen-2-olate, C3H5N2(+)·C10H5O3(-), ab initio calculations of the gas-phase structures of the lawsonate and imidazolium ions were performed to help in the interpretation of the structural features observed. Three different types of hydrogen bond are responsible for the three-dimensional packing of the salt.

A series of mononuclear Co(III) complexes using tridentate N,O-donor ligands: chemical properties and cytotoxicity activity.

Continuing our interest in tridentate ligands to develop new prototypes of cobalt-based metallodrugs for combating cancer, modifications in the backbone of HL1, [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]amine) were proposed in order to modulate the redox potential of new Co(III) complexes. Three ligands with electron withdrawing groups were synthesized: HL2: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]amine); HL3: [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]imine) and HL4: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]imine). They were used to obtain the respective mononuclear complexes 2, 3 and 4, which are discussed compared to the previous reported complex 1 (obtained from HL1).

Synthesis, characterization and biological activities of mononuclear Co(III) complexes as potential bioreductively activated prodrugs.

Aiming to investigate the use of tridentate ligands to develop new bireductively activated prodrugs, two N(2)O-donor ligands (HL1: [(2-hydroxybenzyl)(2-(imidazol-2-yl)ethyl)]amine; and HL2: [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]amine) were used to synthesize new Co(III) complexes, 1 and 2. Both complexes were characterized by X-ray crystallography, mass spectrometry, electrochemistry, IR, UV-visible and (1)H NMR spectroscopies. Electrochemical data in methanol revealed that the Co(III)-->Co(II) reduction of 1 (-0.

Structural changes of hexamethylenetetramine and undecanedioic acid co-crystal (HMT-C11) as a function of the temperature.

HMT-C11 belongs to the family of adducts formed by the co-crystallization of N(4)(CH(2))(6) molecules (hexamethylenetetramine or HMT) and aliphatic dicarboxylic acids HOOC(CH(2))(n - 2)COOH with 5 View Article and Find Full Text PDF

Structural analysis of Tityus serrulatus Ts1 neurotoxin at atomic resolution: insights into interactions with Na+ channels.

The structure of the Ts1 toxin from the Brazilian scorpion Tityus serrulatus was investigated at atomic resolution using X-ray crystallography. Several positively charged niches exist on the Ts1 molecular surface, two of which were found to coordinate phosphate ions present in the crystallization solution. One phosphate ion is bound to the conserved basic Lys1 residue at the Ts1 N-terminus and to residue Asn49.