Chitinase Chit62J4 Essential for Chitin Processing by Human Microbiome Bacterium Clostridium paraputrificum J4.

Commensal bacterium Clostridium paraputrificum J4 produces several extracellular chitinolytic enzymes including a 62 kDa chitinase Chit62J4 active toward 4-nitrophenyl N,N'-diacetyl-ß-d-chitobioside (pNGG). We characterized the crude enzyme from bacterial culture fluid, recombinant enzyme rChit62J4, and its catalytic domain rChit62J4cat. This major chitinase, securing nutrition of the bacterium in the human intestinal tract when supplied with chitin, has a pH optimum of 5.5 and processes pNGG with Km = 0.24 mM and kcat = 30.0 s-1. Sequence comparison of the amino acid sequence of Chit62J4, determined during bacterial genome sequencing, characterizes the enzyme as a family 18 glycosyl hydrolase with a four-domain structure. The catalytic domain has the typical TIM barrel structure and the accessory domains-2x Fn3/Big3 and a carbohydrate binding module-that likely supports enzyme activity on chitin fibers. The catalytic domain is highly homologous to a single-domain chitinase of Bacillus cereus NCTU2. However, the catalytic profiles significantly differ between the two enzymes despite almost identical catalytic sites. The shift of pI and pH optimum of the commensal enzyme toward acidic values compared to the soil bacterium is the likely environmental adaptation that provides C. paraputrificum J4 a competitive advantage over other commensal bacteria.

Tetranuclear Copper(I) Iodide Complexes: A New Class of X-ray Phosphors.

We report intensive visible light radioluminescence upon X-ray irradiation of archetypal tetranuclear copper(I) iodide complexes containing triphenylphosphine or pyridine ligands in the solid state. These properties, attractive for the design of X-ray responsive materials, can be attributed to the heavy {Cu4I4} cubane-like core, the absence of oxygen quenching of the emissive triplet states, and the high photoluminescence quantum yields. Radioluminescence originates from the same emissive triplet states as those produced by ultraviolet excitation as confirmed by the observed radioluminescence thermochromism. The radioluminescence properties are also preserved after incorporation of these complexes into polystyrene films, making them appealing for the development of plastic scintillators.

X-ray Inducible Luminescence and Singlet Oxygen Sensitization by an Octahedral Molybdenum Cluster Compound: A New Class of Nanoscintillators.

Newly synthesized octahedral molybdenum cluster compound (n-Bu4N)2[Mo6I8(OOC-1-adamantane)6] revealed uncharted features applicable for the development of X-ray inducible luminescent materials and sensitizers of singlet oxygen, O2((1)Δg). The compound exhibits a red-NIR luminescence in the solid state and in solution (e.g., quantum yield of 0.76 in tetrahydrofuran) upon excitation by UV-vis light. The luminescence originating from the excited triplet states is quenched by molecular oxygen to produce O2((1)Δg) with a high quantum yield. Irradiation of the compound by X-rays generated a radioluminescence with the same emission spectrum as that obtained by UV-vis excitation. It proves the formation of the same excited triplet states regardless of the excitation source. By virtue of the described behavior, the compound is suggested as an efficient sensitizer of O2((1)Δg) upon X-ray excitation. The luminescence and radioluminescence properties were maintained upon embedding the compound in polystyrene films. In addition, polystyrene induced an enhancement of the radioluminescence intensity via energy transfer from the scintillating polymeric matrix. Sulfonated polystyrene nanofibers were used for the preparation of nanoparticles which form stable dispersions in water, while keeping intact the luminescence properties of the embedded compound over a long time period. Due to their small size and high oxygen diffusivity, these nanoparticles are suitable carriers of sensitizers of O2((1)Δg). The presented results define a new class of nanoscintillators with promising properties for X-ray inducible photodynamic therapy.

A novel amido-pyrophosphate Mn(II) chelate complex with the synthetic ligand O{P(O)[NHC(CH3)3]2}2 (L): [Mn(L)2{OC(H)N(CH3)2}2]Cl2·2H2O.

The title complex, trans-bis(dimethylformamide-κO)bis{N,N'-N'',N'''-tetra-tert-butyl[oxybis(phosphonic diamide-κO)]}manganese(II) dichloride dihydrate, [Mn(C16H40N4O3P2)2(C3H7NO)2]Cl2·2H2O, is the first example of a bis-chelate amido-pyrophosphate (pyrophosphoramide) complex containing an O[P(O)(NH)2]2 fragment. Its asymmetric unit contains half of the complex dication, one chloride anion and one water molecule. The Mn(II) atom, located on an inversion centre, is octahedrally coordinated, with a slight elongation towards the monodentate dimethylformamide ligand. Structural features of the title complex, such as the P=O bond lengths and the planarity of the chelate ring, are compared with those of previously reported complexes with six-membered chelates involving the fragments C(O)NHP(O), (X)NP(O) [X = C(O), C(S), S(O)2 and P(O)] and O[P(O)(N)2]2. This analysis shows that the six-membered chelate rings are less puckered in pyrophosphoramide complexes containing a P(O)OP(O) skeleton, such as the title compound. The extended structure of the title complex involves a linear aggregate mediated by N-H...O and N-H...Cl hydrogen bonds, in which the chloride anion is an acceptor in two additional O-H...Cl hydrogen bonds.

Two polymorphs of bis(2-carbamoylguanidinium) fluorophosphonate dihydrate.

Two polymorphs of bis(2-carbamoylguanidinium) fluorophosphonate dihydrate, 2C(2)H(7)N(4)O(+)·FO(3)P(2-)·2H(2)O, are presented. Polymorph (I), crystallizing in the space group Pnma, is slightly less densely packed than polymorph (II), which crystallizes in Pbca. In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered over two positions, in contrast with its H atoms. The hydrogen-bond patterns in both polymorphs share similar features. There are O-H···O and N-H···O hydrogen bonds in both structures. The water molecules donate their H atoms to the O atoms of the fluorophosphonates exclusively. The water molecules and the fluorophosphonates participate in the formation of R(4)(4)(10) graph-set motifs. These motifs extend along the a axis in each structure. The water molecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N-H···O hydrogen bonds. The water molecules are significant building elements in the formation of a three-dimensional hydrogen-bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen-bond networks of (I) and (II). The N-H···O and O-H···O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N-H···O hydrogen bonds are shorter than the shortest O-H···O hydrogen bonds, which is an unusual feature. The properties of the hydrogen-bond network in (II) can be related to an unusually long P-O bond length for an unhydrogenated fluorophosphonate anion that is present in this structure. In both structures, the N-H···F interactions are far weaker than the N-H···O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).

Mixed crystals of 2-carbamoylguanidinium with hydrogen fluorophosphonate and hydrogen phosphite in the ratios 1:0, 0.76 (2):0.24 (2) and 0.115 (7):0.885 (7).

The title compounds, 2-carbamoylguanidinium hydrogen fluorophosphonate, C(2)H(7)N(4)O(+)·HFO(3)P(-), (I), 2-carbamoylguanidinium-hydrogen fluorophosphonate-hydrogen phosphite (1/0.76/0.24), C(2)H(7)N(4)O(+)·0.76HFO(3)P(-)·0.24H(2)O(3)P(-), (II), and 2-carbamoylguanidinium-hydrogen fluorophosphonate-hydrogen phosphite (1/0.115/0.885), C(2)H(7)N(4)O(+)·0.115HFO(3)P(-)·0.885H(2)O(3)P(-), (III), are isostructural with guanylurea hydrogen phosphite, C(2)H(7)N(4)O(+)·H(2)O(3)P(-) [Fridrichová, Nemec, Císarová & Nemec (2010). CrystEngComm, 12, 2054-2056]. They constitute structures where the hydrogen phosphite anion has been fully or partially replaced by hydrogen fluorophosphonate. The title structures are the fourth example of isostructural compounds which differ by the presence of hydrogen fluorophosphonate and hydrogen phosphite or fluorophosphonate and phosphite anions. Moreover, the present study reports structures with these mixed anions for the first time. In the reported mixed salts, the P and O atoms of either anion overlap almost exactly, as can be judged by comparison of their equivalent isotropic displacement parameters, while the P-F and P-H directions are almost parallel. There are strong O-H···O hydrogen bonds between the anions, as well as strong N-H···O hydrogen bonds between the 2-carbamoylguanidinium cations in the title structures. Altogether they form a three-dimensional hydrogen-bond pattern. Interestingly, rare N-H···F interactions are also present in the title structures. Another exceptional feature concerns the P-O(H) distances, which are about as long as the P-F distance. The dependence of P-F distances on the longest P-O distances in FO(3)P(2-) or HFO(3)P(-) is presented. The greater content of hydrogen phosphite in the mixed crystals causes a larger deformation of the cations from planarity.

Two new XP(O)[NHC(CH3)3]2 phosphoramidates, with X = (CH3)2N and [(CH3)3CNH]2P(O)(O).

In N,N'-di-tert-butyl-N'',N''-dimethylphosphoric triamide, C(10)H(26)N(3)OP, (I), and N,N',N'',N'''-tetra-tert-butyl[oxybis(phosphonic diamide), [corrected] C(16)H(40)N(4)O(3)P(2), (II), the extended structures are mediated by P(O)...(H-N)(2) interactions. The asymmetric unit of (I) consists of six independent molecules which aggregate through P(O)...(H-N)(2) hydrogen bonds, giving R(2)(1)(6) loops and forming two independent chains parallel to the a axis. Of the 12 independent tert-butyl groups, five are disordered over two different positions with occupancies ranging from 1/6 to 5/6. In the structure of (II), the asymmetric unit contains one molecule. P(O)...(H-N)(2) hydrogen bonds give S(6) and R(2)(2)(8) rings, and the molecules form extended chains parallel to the c axis. The structures of (I) and (II), along with similar structures having (N)P(O)(NH)(2) and (NH)(2)P(O)(O)P(O)(NH)(2) skeletons extracted from the Cambridge Structural Database, are used to compare hydrogen-bond patterns in these families of phosphoramidates. The strengths of P(O)[...H-N](x) (x = 1, 2 or 3) hydrogen bonds are also analysed, using these compounds and previously reported structures with (N)(2)P(O)(NH) and P(O)(NH)(3) fragments.

4-[(E)-(4-Eth-oxy-phen-yl)imino-meth-yl]phenol.

In the title compound, C(15)H(15)NO(2), the dihedral angle between the benzene rings is 52.04 (5)° and the mol-ecule has an E conformation about the central C=N bond. In the crystal, mol-ecules are connected by O-H⋯N hydrogen bonds, forming zigzag chains along the b axis. The crystal packing also features weak C-H⋯O inter-actions.

[N,N'-Bis(2,3,4-trimeth-oxy-benzyl-idene)-ethane-1,2-diamine-κ(2)N,N']dibromido-mercury(II).

In the title compound, [HgBr(2)(C(22)H(28)N(2)O(6))], the Hg(II) ion is bonded to two Br(-) ions and two N atoms of the chelating Schiff base ligand in a distorted tetra-hedral geometry. The Schiff base ligand adopts an E,E conformation. The dihedral angle between the planes of the two halves of the central N,N'-dimethyl-ethylenediamine part of the ligand is 2.3 (11)°. The crystal studied was twinned by pseudomerohedry [twin law (0-10/-100/00-1)]; the contribution of the minor twin component refined to 0.208 (3).

2-[(4-Meth-oxy-2-nitro-phen-yl)imino-meth-yl]phenol.

The crystal structure of the title compound, C(14)H(12)N(2)O(4), contains four crystallographically independent mol-ecules in the asymmetric unit. All the mol-ecules have similar conformations; the dihedral angles between the aromatic rings are 33.1 (1), 33.76 (9), 31.41 (9) and 32.56 (10)°. Intra-molecular O-H⋯N hydrogen bonds form S(6) ring motifs in each molecule. In the crystal, there are two pairs of pseudo-inversion-related mol-ecules. Along the c axis, mol-ecules are stacked with π-π inter-actions between the 2-hy-droxy-phenyl and 4-meth-oxy-2-nitro-phenyl rings [centroid-centroid distances = 3.5441 (12)-3.7698 (12) Å].

(1H-Benzimidazol-1-yl)methanol.

In the title compound, C(8)H(8)N(2)O, the N-CH(2) and CH(2)-O bond lengths can be correlated to the manifestation of an anomeric effect in the N-CH(2)-O moiety. In the crystal, inter-molecular O-H⋯N hydrogen bonds link the mol-ecules into zigzag chains, with graph-set motif C(6), parallel to [001]. These chains are further linked into sheets by weak nonclassical C-H⋯O hydrogen bonds.

3,3'-(Ethane-1,2-di-yl)bis-(3,4-dihydro-2H-1,3-benzoxazine).

The title compound, C(18)H(20)N(2)O(2), was prepared by Mannich-type reaction of phenol, ethane-1,2-diamine and formaldehyde. The heterocyclic rings adopt half-chair conformations. The acyclic methyl-ene groups attached to the N atoms are in an axial position. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into dimers. These dimers are further connected via C-H⋯π contacts.

Tris(2-carbamoylguanidinium) hydrogen fluoro-phospho-nate fluoro-phospho-nate monohydrate.

The title structure, 3C(2)H(7)N(4)O(+)·HFPO(3) (-)·FPO(3) (2-)·H(2)O, contains three independent 2-carbamoylguanidinium cations, one fluoro-phospho-nate, one hydrogen fluoro-phospho-nate and one water mol-ecule. There are three different layers in the structure that are nearly perpendicular to the c axis. Each layer contains a cation and the layers differ by the respective presence of the water mol-ecule, the hydrogen fluoro-phospho-nate and fluoro-phospho-nate anions. N-H⋯O hydrogen bonds between the guanylurea mol-ecules that inter-connect the mol-ecules within each layer are strong. The layers are inter-connected by strong and weak O-H⋯O hydrogen bonds between the anions and water mol-ecules, respectively. Inter-estingly, the configuration of the layers is quite similar to that observed in 2-carbamoylguanidinium hydrogen fluoro-phospho-nate [Fábry et al. (2012). Acta Cryst. C68, o76-o83]. There is also present a N-H⋯F hydrogen bond in the structure which occurs quite rarely.

[4-Bromo-N-(pyridin-2-yl-methyl-idene)aniline-κ(2)N,N']iodido(triphenyl-phosphane-κP)copper(I).

In the title compound, [CuI(C(12)H(9)BrN(2))(C(18)H(15)P)], the Cu(I) ion is bonded to one I atom, one triphenyl-phosphane P atom and two N atoms of the diimine ligand in a distorted tetra-hedral geometry. The Schiff base acts as a chelating ligand and coordinates to the Cu(I) atom via two N atoms. In the diimine ligand, the dihedral angle between the pyridine and bromo-phenyl rings is 19.2 (2)°. In the crystal, mol-ecules are connected by π-π stacking inter-actions between inversion-related pyridine rings [centroid-centroid distance = 3.404 (3) Å].

[N,N'-Bis(2,6-dichloro-benzyl-idene)propane-1,3-diamine-κ(2)N,N']dibromidozinc.

In the title compound, [ZnBr(2)(C(17)H(14)Cl(4)N(2))], the Zn(II) ion is bonded to two bromide ions and two N atoms of the diimine ligand and displays a moderately distorted tetra-hedral coordination geometry. The Schiff base ligand acts as a chelating ligand and coordinates to the Zn(II) atom via two N atoms.

6H,13H-5,12:7,14-Dimethano-dinaphtho-[2,3-d:2,3-i][1,3,6,8]tetra-azecine.

In the title compound, C(24)H(20)N(4), obtained through the condensation of naphthalene-2,3-diamine with formaldehyde in methanol, the mol-ecule is located on a special position of site symmetry -4. Due to symmetry considerations, the aromatic rings are strictly perpendicular to each other. In the crystal, mol-ecules are linked by pairs of C-H⋯π inter-actions into columns along [110].

N-[Amino(imino)methyl]uronium tetrafluoroborate.

In the title compound, C(2)H(7)N(4)O(+)·BF(4) (-), inter-molecular N-H⋯O hydrogen bonds connect the cations into chains parallel to the c axis, with graph-set motif C(4). These chains are in turn connected into a three-dimensional network by inter-molecular N-H⋯F hydrogen bonds. The B-F distances distances in the anion are not equal.

1,3-Dinitro-soimidazolidine.

The title compound, C(3)H(6)N(4)O(2), exhibits partial disorder with the refined occupancy ratios of the two components being 0.582 (5):0.418 (5). In the major component, the nitroso groups have a relative syn spatial arrangement [O=N⋯N=O pseudo-torsion angle = 1.1 (4)°], whereas the other component has an anti disposition [177.6 (1)°]. The N-N=O moieties are almost coplanar with a dihedral angle of 5.3 (3)°, while in the minor occupied set of atoms, this angle is 8 (1)°. In both components, the imidazolidine ring adopts a twisted conformation on the C-C bond and the crystal structure shows the strain of this ring according to the N-CH(2)-CH(2)-N torsion angles [25.9 (5) and -23.8 (7)°]. In the crystal, molecules are linked by weak C-H⋯O hydrogen bonds.

(E)-4-[(4-Bromo-phen-yl)imino-meth-yl]-2-meth-oxy-phenol.

In the crystal structure of the title compound, C(14)H(12)BrNO(2), the dihedral angle between the rings is 37.87 (10)° and the mol-ecule has an E conformation about the central C=N bond. In the crystal, mol-ecules are connected by inter-molecular O-H⋯N hydrogen bonds into zigzag chains running parallel to the b axis. The packing also features C-H⋯O inter-actions.

1,1'-[Imidazolidine-1,3-diylbis(methyl-ene)]bis-(1H-benzotriazole).

In the title compound, C(17)H(18)N(8), the imidazolidine ring adopts an envelope conformation with the substituents at the N atoms in trans positions with respect to the central ring. The dihedral angle between the two benzotriazole rings is 71.65 (10)°. In the crystal, non-classical C-H⋯N inter-actions link the mol-ecules into helical chains along the b axis. The crystal packing is further stabilized by weak C-H⋯π inter-actions.