Six novel uranyl terpyridine aromatic carboxylate coordination polymers, [UO(2)(C(6)H(2)O(4)S)(C(15)H(11)N(3))] (1), [UO(2)(C(6)H(2)O(4)S)(C(15)H(10)N(3)Cl)]·H(2)O (2), [UO(2)(C(8)H(4)O(4))(C(15)H(11)N(3))] (3), [UO(2)(C(8)H(4)O(4))(C(15)H(10)N(3)Cl)] (4), [UO(2)(C(12)H(6)O(4))(C(15)H(11)N(3))] (5), and [UO(2)(C(12)H(6)O(4))(C(15)H(10)N(3)Cl)] (6), were synthesized under solvothermal conditions and characterized by single-crystal and powder X-ray diffraction and luminescence and UV-vis spectroscopy. Compounds 1, 2, and 5 crystallize as molecular uranyl dimers, whereas compounds 3, 4, and 6 contain ladder motifs of uranyl centers. Fluorescence spectra of 1-4 show characteristic UO(2)(2+) emission, wherein bathochromic and hypsochromic shifts are noted as a function of organic species. In contrast, uranyl emission from 5 and 6 is quenched by the naphthalene dicarboxylic acid linker molecules.

Thiophene 2,5-dicarboxylic acid (TDC) was reacted with uranyl acetate dihydrate and one (or none) of six N-donor chelating ligands (2,2′-bipyridine (BPY), 4,4′-dimethyl-2,2′-bipyridine (4-MeBPY), 5,5′-dimethyl-2,2′-bipyridine (5-MeBPY), 6,6′-dimethyl-2,2′-bipyridine (6-MeBPY), 4,4′,6,6′-tetramethyl-2,2′-bipyridine (4,6-MeBPY), and tetrakis(2-pyridyl)pyrazine (TPPZ) to result in the crystallization of seven uranyl coordination polymers, which were characterized by their crystal structures and luminescence properties. The seven coordination polymers, Na 2 [(UO 2 ) 2 (C 6 H 2 O 4 S) 3 ]· (7), consist of either uranyl hexagonal bipyramidal or pentagonal bipyramidal coordination geometries. In all structures, structural variations in the local and global structures of 1−7 are influenced by the positions (or number) of methyl groups or pyridyl rings on the N-donor species, thus resulting in a wide diversity of structures ranging from single chains, double chains, or 2-D sheets. Direct coordination of N-donor ligands to uranyl centers is observed in the chain structures of 2−4 using BPY, 4-MeBPY, and 5-MeBPY, whereas the N-donor species participate as guests (as either neutral or charge balancing species) in the chain and sheet structures of 5−7 using 6-MeBPY, 4,6-MeBPY, and TPPZ, respectively. Compound 1 is the only structure that does not contain any N-donor ligands and thus crystallizes as a 2-D interpenetrating sheet. The luminescent properties of 1−7 are influenced by the direct coordination or noncoordination of N-donor species to uranyl centers. Compounds 2−4 exhibit typical UO 2 2+ emission upon direct coordination of N-donors, but its absence is observed in 1, 5, 6, and 7, when N-donor species participate as guest molecules. These results suggest that direct coordination of N-donor ligands participate as chromophores, thus resulting in possible UO 2 2+ sensitization. The lack of emission in 1, 5, 6, and 7 may be explained by the extended conjugation of the TDC ligands within their structures. ■ INTRODUCTIONCoordination polymers (CPs) constructed from the uranyl cation (UO 2 2+ ) continue to remain attractive in the field of hybrid materials owing to their unique structural and luminescent properties. 1 The UO 2 2+ cation is a linear triatomic species that contains two axial oxygen atoms about the central uranium atom, the terminal nature of which promotes additional ligand coordination about the equatorial plane. 2 This results in three types of UO 2 2+ primary building units (PBUs) found as square, pentagonal, or hexagonal bipyramidal geometries. The uranyl cation may also undergo hydrolysis and subsequent condensation to form secondary building units (SBUs) in the form of dimers, trimers, or tetramers, etc. 3,4 UO 2 2+ hydrolysis under hydrothermal conditions is a dynamic process wherein multiple speciation products are present in a wide range of pH and concentration. 5−7 This, in turn, makes it challenging to predict or control the type of uranyl building unit that will ultimately be observed in the solid st...

Three novel uranyl(VI) peroxide complexes, [(UO2)2(CH3COO)2(O2)(C10H8N2)] (1), [(UO2)2(CH3COO)2(O2)(C12H12N2)] (2), and [(UO2)3(CH3COO)4(O2)(C15H11N3)2] (3), have been synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and luminescence spectroscopy. Each of these structures feature a [(UO2)2(O2)] dimer with additional coordination by acetate, 2,2'-bipyridine (BPY), 5,5'-dimethyl-2,2'-bipyridine (MeBPY), or 2,2':6,2″-terpyridine (TPY). Compound 3 consists of an additional uranyl unit functionalized with a TPY donor ligand. The presence of the peroxo ligand in 1-3 is due to in situ generation of peroxide when preparative solutions of 1-3 were exposed to ambient light and/or sunlight.

Novel therapeutics to overcome the toxic effects of organophosphorus (OP) chemical agents are needed due to the documented use of OPs in warfare (e.g. 1980-1988 Iran/Iraq war) and terrorism (e.g. 1995 Tokyo subway attacks). Standard OP exposure therapy in the United States consists of atropine sulfate (to block muscarinic receptors), the acetylcholinesterase (AChE) reactivator (oxime) pralidoxime chloride (2-PAM), and a benzodiazepine anticonvulsant to ameliorate seizures. A major disadvantage is that quaternary nitrogen charged oximes, including 2-PAM, do not cross the blood brain barrier (BBB) to treat brain AChE. Therefore, we have synthesized and evaluated pro-2-PAM (a lipid permeable 2-PAM derivative) that can enter the brain and reactivate CNS AChE, preventing seizures in guinea pigs after exposure to OPs. The protective effects of the pro-2-PAM after OP exposure were shown using a) surgically-implanted radiotelemetry probes for electroencephalogram (EEG) b) neurohistopathology of brain, c) cholinesterase activities in the PNS and CNS, and d) survivability. The PNS oxime 2-PAM was ineffective at reducing seizures/ status epilepticus (SE) in diisopropyl-fluorophosphate (DFP)-exposed animals. In contrast, pro-2-PAM significantly suppressed and then eliminated seizure activity. In OP-exposed guinea pigs, there was a significant reduction in neurological damage with pro-2-PAM, but not 2-PAM. Distinct regional areas of the brains showed significantly higher AChE activity 1.5 h after OP exposure in pro-2-PAM treated animals compared to the 2-PAM treated ones. However, blood and diaphragm showed similar AChE activities in animals treated with either oxime, as both 2-PAM and pro 2-PAM are PNS active oximes. In conclusion, pro-2-PAM can cross the BBB, is rapidly metabolized inside the brain to 2-PAM, and protects against OP-induced SE through restoration of * Corresponding author. Tel: +1 301 319 9987; fax: +1 301 319 9070. Richard.Gordon@amedd.army.mil.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access