Tiffany L. Kinnibrugh

Kinetic hysteresis in gas adsorption behavior for a rigid MOF arising from zig-zag channel structures

A new porous MOF, Zn(TBC)2·{guest}, is synthesized and studied by the single crystallography, N2 isothermal adsorption and GC separation of CO2 from air. This MOF shows large hysteresis on N2 adsorption at 77 K up to a P/Po of 0.9, which arises from the unique zig-zag channel structures of the framework. The MOF shows promising separation ability for CO2 from air.

Spectroscopic, cyto-, and photo-toxicity studies of substituted piperidones: potential sensitizers for two-photon photodynamic therapy

Two-photon photodynamic therapy has the advantages of being highly localized in its effects and allows for deeper tissue penetration, when compared to one-photon photodynamic therapy. N-alkylated 3,5-bis(arylidene)-4-piperidones, with a donor-pi-acceptor-pi-donor structure, have the potential to be useful two-photon sensitizers. We have measured two-photon cross sections (using femtosecond excitation), fluorescence quantum yields, fluorescence lifetimes, and xray crystal structures for a number of these compounds. Most two-photon cross sections are comparable to or larger than that of Rhodamine B. However, the fluorescence quantum yields are low (all less than 10%) and the fluorescence lifetimes are less than 1 ns (with one exception), suggesting that there may be a significant energy transfer to the triplet state. This would encourage singlet oxygen formation and increase cellular toxicity. Results of dark cyto-toxicity studies with several human cancer cell lines are presented. White light photo-toxicity results are also presented, and suggest that increasing the number of double bonds, from one to two, in the piperidone wings increases the photo-toxicity with little corresponding change in the dark cyto-toxicity.

From small structural modifications to adjustment of structurally dependent properties: 1-methyl-3,5-bis[(E)-2-thienylidene]-4-piperidone and 3,5-bis[(E)-5-bromo-2-thienylidene]-1-methyl-4-piperidone.

The molecules of the title compounds, C(16)H(15)NOS(2), (I), and C(16)H(13)Br(2)NOS(2), (II), are E,E-isomers and consist of an extensive conjugated system, which determines their molecular geometries. Compound (I) crystallizes in the monoclinic space group P2(1)/c. It has one thiophene ring disordered over two positions, with a minor component contribution of 0.100 (3). Compound (II) crystallizes in the noncentrosymmetric orthorhombic space group Pca2(1) with two independent molecules in the unit cell. These molecules are related by a noncrystallographic pseudo-inversion center and possess very similar geometries. The crystal packings of (I) and (II) have a topologically common structural motif, viz. stacks along the b axis, in which the molecules are bound by weak C-H...O hydrogen bonds. The noncentrosymmetric packing of (II) is governed by attractive intermolecular Br...Br and Br...N interactions, which are also responsible for the very high density of (II) (1.861 Mg m(-3)).

Supramolecular synthesis based on piperidone derivatives and pharmaceutically acceptable co-formers.

The target complexes, bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} butanedioate, 2C27H36N3O(+)·C4H4O4(2-), (II), and bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} decanedioate, 2C27H36N3O(+)·C10H16O4(2-), (III), were obtained by solvent-mediated crystallization of the active pharmaceutical ingredient (API) (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone and pharmaceutically acceptable dicarboxylic (succinic and sebacic) acids from ethanol solution. They have been characterized by melting point, IR spectroscopy and single-crystal X-ray diffraction. For the sake of comparison, the structure of the starting API, (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone methanol monosolvate, C27H35N3O·CH4O, (I), has also been studied. Compounds (II) and (III) represent salts containing H-shaped centrosymmetric hydrogen-bonded synthons, which are built from two parallel piperidinium cations and a bridging dicarboxylate dianion. In both (II) and (III), the dicarboxylate dianion resides on an inversion centre. The two cations and dianion within the H-shaped synthon are linked by two strong intermolecular N(+)-H···(-)OOC hydrogen bonds. The crystal structure of (II) includes two crystallographically independent formula units, A and B. The cation geometries of units A and B are different. The main N-C6H4-C=C-C(=O)-C=C-C6H4-N backbone of cation A has a C-shaped conformation, while that of cation B adopts an S-shaped conformation. The same main backbone of the cation in (III) is practically planar. In the crystal structures of both (II) and (III), intermolecular N(+)-H···O=C hydrogen bonds between different H-shaped synthons further consolidate the crystal packing, forming columns in the [100] and [101] directions, respectively. Salts (II) and (III) possess increased aqueous solubility compared with the original API and thus enhance the bioavailability of the API.