Expression, purification, crystallization and initial crystallographic characterization of the p-hydroxybenzoate hydroxylase from Corynebacterium glutamicum

PHBH from Corynebacterium glutamicum was crystallized using the hanging-drop vapour-diffusion method in the presence of NaH2PO4 and K2HPO4 as precipitants. X-ray diffraction data were collected to a maximum resolution of 2.5 Å on a synchrotron beamline

Single-crystal structure of fully dehydrated and largely NH(4)(+)-exchanged zeolite Y (FAU, Si/Al=1.70), vertical bar(NH(4))(60)Na(11)vertical bar[Si(121)Al(71)O(384)]-FAU

The single-crystal structure of largely ammonium-exchanged zeolite Y dehydrated at room temperature (293 K) and 1 x 10(-6) Torr. has been determined using synchrotron X-radiation in the cubic space group Fd (3) over barm (a 24.9639(2) angstrom) at 294 K. The structure was refined to the final error index R-1 = 0.0429 with 926 reflections where F-o > 4 sigma(F-o); the composition (best integers) was identified as vertical bar(NH4)(60)Na-11 vertical bar[Si121Al71O384]-FAU. The 11 Na+ ions per unit cell were found at three different crystallographic sites and 60 NH4+ ions were distributed over three sites. The 3 Na+ ions were located at site I, the center of the hexagonal prism (Na-O = 2.842(5) angstrom and O-Na-O = 85.98(12)degrees). The 4 Na+ and 22 NH4+ ions were Pound at site I' in the sodalite cavity opposite the double 6-rings, respectively (Na-O = 2.53(13) angstrom, O-Na-O = 99.9(7)degrees, N-O = 2.762(11) angstrom, and O-N-O = 89.1(5)degrees). About 4 Na+ ions occupied site II (Na-O = 2.40(4) angstrom and O-Na-O = 108.9(3)degrees) and 29 NH4+ ions occupy site II (N-O = 2.824(9) angstrom and O-N-O = 87.3(3)degrees) opposite to the single 6-rings in the supercage. The remaining 9 NH4+ ions were distributed over site III' (N-O = 2.55(3), 2.725(13) angstrom and O-N-O = 94.1(13), 62.16(15), 155.7(14)degrees)

Two octanuclear gallium metallamacrocycles of topologically different connectivities

Two topologically different metallamacrocycles - S8 symmetric octanuclear gallium(iii) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(iii) metalladiazamacrocycle - could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues.close131

Steric control of the nuclearity of metallamacrocycles: formation of a hexanuclear gallium metalladiazamacrocycle and a hexadecanuclear manganese metalladiazamacrocycle

An S-6-symmetric hexanuclear gallium metalladiazamacrocycle, [Ga-III (6L6S6)-S-2] with a-(Lambda Delta)(Lambda Delta)-chiral sequence and an S-8-symmetric hexadecanuclear manganese metalladiazamacrocycle, [Mn-III (16L16S16)-S-2] with a-(Lambda Lambda Delta Delta)(Lambda Lambda Delta Delta)-chiral sequence were prepared using the same N-2-trans-cinnamoyl-2-hydroxy-3- naphthoylhydrazide (H3L2) as a bridging pentadentate ligand between the metal centers for the formation of a macrocyclic system.close252

Porous metal-organic frameworks based on metal-organic polyhedra with nanosized cavities as supramolecular building blocks: Two-fold interpenetrating primitive cubic networks of [CU6L8](12+) nanocages

Discrete metal-organic polyhedra (MOP) with nanosized cavities and/or clusters of MOP could be prepared when C3-symmetric facial ligands and a potential hexatopic Cu(II) ion are combined in the presence of perchlorate as a weak linker, while similar reaction conditions in the presence of a nitrate linker led to extended metal-organic frameworks made of MOP as supramolecular building blocks.close414

Novel 48-membered hexadecanuclear and 60-membered icosanuclear manganese metallamacrocycles

Either an S-8 symmetrical 48-membered hexadecanuclear or an S-10 symmetrical 60-membered icosanuclear manganese metallamacrocycle was self-assembled using a manganese ion and a ditopic pentadentate ligand. This was either N-4-phenylbenzoylsalicylhydrazide (H(3)pbshz) containing a rigid rod-shaped, bulky biphenyl residue as a terminal N-acyl group or N-3,3-diphenylpropionylsalicylhydrazide (H(3)dppshz) containing a flexible beta-branched N-acyl group, but with two sterically bulky phenyl residues at the C beta position. The backbone of these metal-organic assemblies is a repeating unit consisting of a -[Mn-N-N-] link that extends to complete either the 48-membered cyclic structure involving 16 manganese(III) centers and 16 ditopic linker ligands or the 60-membered cyclic structure involving 20 manganese(III) centers and 20 ditopic linker ligands (depending on the ligand used). Even though the nuclearity of the metallamacrocycles was different, the successive manganese centers were in the same chiral sequence, ...(Lambda Lambda Delta Delta)(Lambda Lambda Delta Delta)...close333

A dodecanuclear metallamacrocycle having a multidentate bridging ligand in two different binding modes

The reaction of Mn(OAc)2??4H2O with 2,6-dimethoxybenzoylsalicylhydrazide (H3dmbshz) leads to a dodecanuclear manganese metallamacrocycle [Mn12(dmbshz) 12(EtOH)6], 1. The successive manganese centers are connected by the hydrazide N-N groups of the ligands in an alternating pentadentate binding mode, hexadentate binding mode. The alternation results in two alternating chelation modes around the metal centers, a tridentate- tridentate chelation mode and a bidentate-tridentate chelation mode. The metal ions in 1 are in a ⋯(AA??BC A??B)(AA??BC A??B)⋯ chiral sequence, the alternation of the chiralities expanding the cyclic ring system to a 36-membered dodecanuclear manganese metallamacrocyclic ring system with S6 point group symmetry.close9