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1.  A boronate prochelator built on a triazole framework for peroxide-triggered tridentate metal binding 
Inorganica chimica acta  2012;393:294-303.
Iron chelating agents have the potential to minimize damage associated with oxidative stress in a range of diseases; however, this potential is countered by risks of indiscriminant metal binding or iron depletion in conditions not associated with systemic iron overload. Deferasirox is a chelator used clinically for iron overload, but also is cytotoxic to cells in culture. In order to test whether a prodrug version of deferasirox could minimize its cytotoxicity but retain its protective properties against iron-induced oxidative damage, we synthesized a prochelator that contains a self-immolative boronic ester masking group that is removed upon exposure to hydrogen peroxide to release the bis-hydroxyphenyltriazole ligand deferasirox. We present here the synthesis and characterization of this triazole-based, self-immolative prochelator: TIP (4-(5-(2-((4-boronobenzyl)oxy)phenyl)-3-(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl)benzoic acid). TIP does not coordinate to Fe3+ and shows only weak affinity for Cu2+ or Zn2+, in stark contrast to deferasirox, which avidly binds all three metal ions. TIP converts efficiently in vitro upon reaction with hydrogen peroxide to deferasirox. In cell culture, TIP protects retinal pigment epithelial cells from death induced by hydrogen peroxide; however, TIP itself is more cytotoxic than deferasirox in unstressed cells. These results imply that the cytotoxicity of deferasirox may not derive exclusively from its iron withholding properties.
doi:10.1016/j.ica.2012.06.011
PMCID: PMC3579658  PMID: 23439614
Chelation therapy; Iron; Oxidative stress; Fenton chemistry; Reactive oxygen species; Prodrug
2.  Dilithium 1,2,5-thia­diazo­lidine-3,4-dione 1,1-dioxide dihydrate 
The title compound, poly[μ-aqua-aqua-μ6-(1,1-dioxo-1λ6,2,5-thia­diazo­lidine-3,4-diolato)-dilithium], [Li2(C2N2O4S)(H2O)2]n or (H2O)2:Li2TDD, forms an infinite three-dimensional structure containing five-coordinate (Li/5) and six-coordinate (Li/6) Li+ cations. Li/5 is coordinated by three water mol­ecules, one carbonyl O atom and one sulfuryl O atom while Li/6 is coordinated by one water mol­ecule, three carbonyl O atoms, and two sulfuryl O atoms. Each water mol­ecule bridges two Li+ cations, while also hydrogen bonding to either one endocyclic N atom and one sulfuryl O atom or two endocyclic N atoms. While the endocyclic N atoms in the anion do not coordinate the Li+ cations, the carbonyl and sulfuryl groups each coordinate three Li+ cations, which gives rise to the infinite three-dimensional structure.
doi:10.1107/S1600536812036379
PMCID: PMC3435632  PMID: 22969505
3.  Lithium bis­(2-methyl­lactato)borate monohydrate 
The title compound {systematic name: poly[[aqua­lithium]-μ-3,3,8,8-tetra­methyl-1,4,6,9-tetra­oxa-5λ4-borataspiro­[4.4]nonane-2,7-dione]}, [Li(C8H12BO6)(H2O)]n (LiBMLB), forms a 12-membered macrocycle, which lies across a crystallographic inversion center. The lithium cations are pseudo-tetra­hedrally coordinated by three methyl­lactate ligands and a water mol­ecule. The asymmetric units couple across crystallographic inversion centers, forming the 12-membered macrocycles. These macrocycles, in turn, cross-link through the Li+ cations, forming an infinite polymeric structure in two dimensions parallel to (101).
doi:10.1107/S1600536812017540
PMCID: PMC3379088  PMID: 22719309
4.  Tetra­kis(acetonitrile-κN)lithium hexa­fluoridophosphate acetonitrile monosolvate 
In the title compound, [Li(CH3CN)4]PF6·CH3CN, the asymmetric unit consists of three independent tetra­hedral [Li(CH3CN)4]+ cations, three uncoordinated PF6 − anions and three uncoordinated CH3CN solvent mol­ecules. The three anions are disordered over two sites through a rotation along one of the F—P—F axes. The relative occupancies of the two sites for the F atoms are 0.643 (16):0.357 (16), 0.677 (10):0.323 (10) and 0.723 (13):0.277 (13). The crystal used was a racemic twin, with approximately equal twin components.
doi:10.1107/S1600536811027528
PMCID: PMC3212250  PMID: 22090907
5.  Poly[diacetonitrile­[μ3-difluoro­(oxalato)borato]sodium] 
The title compound, [Na(C2BF2O4)(CH3CN)2]n, forms infinite two-dimensional layers running parallel to (010). The layers lie across crystallographic mirror planes at y = 1/4 and 3/4. The Na, B and two F atoms reside on these mirror planes. The Na+ cations are six-coordinate. Two equatorial coordination positions are occupied by acetonitrile mol­ecules. The other two equatorial coordination sites are occupied by the chelating O atoms from the difluoro­(oxalato)borate anion (DFOB−). The axial coordination sites are occupied by two F atoms from two different DFOB− anions.
doi:10.1107/S1600536811015091
PMCID: PMC3120346  PMID: 21754586
6.  Poly[bis­(acetonitrile-κN)bis­[μ3-bis(tri­fluoro­methane­sulfonyl)­imido-κ4 O,O′:O′′:O′′′]dilithium] 
In the title compound, [Li2(CF3SO2NSO2CF3)2(CH3CN)2]n, two Li+ cations reside on crystallographic inversion centers, each coordinated by six O atoms from bis(trifluoromethanesulfonyl)imide (TFSI−) anions. The third Li+ cation on a general position is four-coordinated by two anion O atoms and two N atoms from acetonitrile mol­ecules in a tetra­hedral geometry.
doi:10.1107/S1600536811011561
PMCID: PMC3089180  PMID: 21754274
7.  Lithium difluoro­(oxalato)borate tetra­methyl­ene sulfone disolvate 
The title compound, Li+·C2BF2O4 −·2C4H8O2S, is a dimeric species, which resides across a crystallographic inversion center. The dimers form eight-membered rings containing two Li+ cations, which are joined by O2S sulfone linkages. The Li+ cations are ligated by four O atoms from the anions and solvent mol­ecules, forming a pseudo-tetra­hedral geometry. The exocyclic coordination sites are occupied by O atoms from the oxalate group of the difluoro­(oxalato)borate anion and an additional tetra­methyl­ene sulfone ligand.
doi:10.1107/S1600536811011743
PMCID: PMC3089187  PMID: 21754273
8.  Poly[[(acetonitrile)­lithium(I)]-μ3-tetra­fluoridoborato] 
The structure of the title compound, [Li(BF4)(CH3CN)]n, consists of a layered arrangement parallel to (100) in which the Li+ cations are coordinated by three F atoms from three tetra­fluoridoborate (BF4 −) anions and an N atom from an acetonitrile mol­ecule. The BF4 − anion is coordinated to three different Li+ cations though three F atoms. The structure can be described as being built from vertex-shared BF4 and LiF3(NCCH3) tetra­hedra. These tetra­hedra reside around a crystallographic inversion center and form 8-membered rings.
doi:10.1107/S1600536811012141
PMCID: PMC3089248  PMID: 21754284
9.  Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. III. Spectral and structural properties 
Tetrahedron  2007;63(18):3850-3863.
The availability of stable chlorins bearing few or no substituents has enabled a variety of fundamental studies. The studies described herein report absorption spectra of diverse chlorins, comparative NMR features of chlorins bearing 0–3 meso-aryl substituents, and X-ray structures of the fully unsubstituted chlorin and the oxochlorin.
doi:10.1016/j.tet.2007.02.040
PMCID: PMC1865128  PMID: 17479169
Chlorin; NMR; Absorption spectra; X-ray

Results 1-9 (9)