Lipophilic Ga Complex with Broad-Spectrum Antimicrobial Activity and the Ability to Overcome Gallium Resistance in both and .

Antibiotic resistance (AR) necessitates the discovery of new antimicrobials with alternative mechanisms of action to those employed by conventional antibiotics. One such strategy utilizes Ga to target iron metabolism, a critical process for survival. Still, Ga-based therapies are generally ineffective against Gram-positive bacteria and promote Ga resistance.

One-Pot Self-Assembly of Dinuclear, Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core.

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO, CHCO, Cl, NO), sodium azide (NaN), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence CoCo: [Co(HL)(AP)(N)](ClO) (), [Co(HL)(µ-1,1,1-N)(µ-1,1-N)Cl(CHOH)]·4CHOH (), [CoCo(HL)(µ-CHCO)(µ-OH)](NO)·2CHCHOH (), and [CoCo (HL1)(THMAM)](NO) (). In , two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.

Self-Assembly of Antiferromagnetically-Coupled Copper(II) Supramolecular Architectures with Diverse Structural Complexities.

The self-assembly of 2,6-diformyl-4-methylphenol () and 1-amino-2-propanol ()/2-amino-1,3-propanediol () in the presence of copper(II) ions results in the formation of six new supramolecular architectures containing two versatile double Schiff base ligands (HL and HL1) with one-, two-, or three-dimensional structures involving diverse nuclearities: tetranuclear [Cu(HL)(N)]·4CHOH·56HO () and [Cu(L)(OH)(HO)] (), dinuclear [Cu(HL1)(N)(HO)(NO)] (), polynuclear {[Cu(HL1)(HO)(BF)(N)]·HO} (), heptanuclear [Cu(HL1)(O)(CHCO)]·6CHOH·44HO (), and decanuclear [Cu(HL1)(O)(OH)(CHCO)] (CHCO)·20HO (). X-ray studies have revealed that the basic building block in , , and is comprised of two copper centers bridged through one μ-phenolate oxygen atom from HL or HL1, and one μ-1,1-azido (N) ion and in , , and by μ-phenoxide oxygen of L or HL1 and μ-O or μ-O ions. H-bonding involving coordinated/uncoordinated hydroxy groups of the ligands generates fascinating supramolecular architectures with 1D-single chains ( and ), 2D-sheets (), and 3D-structures ().

A Flexible Strategy for Modular Synthesis of Curcuminoid-BF /Curcuminoid Pairs and Their Comparative Antiproliferative Activity in Human Cancer Cell Lines.

A facile protocol that enables synthetic interconversion of CUR-BF and CUR compounds is described that significantly widens the preparative scope of curcuminoids, providing access to larger libraries of compounds, thus enabling comparative antiproliferative and apoptotic study of a larger library of synthetic analogs in cancer cell lines.

Deuterated Curcuminoids: Synthesis, Structures, Computational/Docking and Comparative Cell Viability Assays against Colorectal Cancer.

A series of deuterated curcuminoids (CUR) were synthesized, bearing two to six OCD groups, in some cases in combination with methoxy groups, and in others together with fluorine or chlorine atoms. A model ring-deuterated hexamethoxy-CUR-BF and its corresponding CUR compound were also synthesized from a 2,4,6-trimethoxybenzaldehyde-3,5-d precursor. As with their protio analogues, the deuterated compounds were found to remain exclusively in the enolic form.

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts.

A series of giant tris(heteroaryl)methanes are easily assembled by one-pot three-component synthesis by simple reflux in ethanol without catalyst or additives. Diversely substituted indoles (Ar) react with quinoline aldehydes, quinolone aldehydes, chromone aldehydes, and fluorene aldehydes (ArCHO) and coumarins (Ar) in 1:1:1 ratio to form the corresponding tris(heteroaryl)methanes (ArArAr)CH along with (ArArAr)CH triads. A series of new 2:1 triads were also synthesized by coupling substituted indoles with ArCHO.

Tuning charge carrier transport and optical birefringence in liquid-crystalline thin films: A new design space for organic light-emitting diodes.

Liquid-crystalline organic semiconductors exhibit unique properties that make them highly interesting for organic optoelectronic applications. Their optical and electrical anisotropies and the possibility to control the alignment of the liquid-crystalline semiconductor allow not only to optimize charge carrier transport, but to tune the optical property of organic thin-film devices as well. In this study, the molecular orientation in a liquid-crystalline semiconductor film is tuned by a novel blading process as well as by different annealing protocols.

Minority Currents in n-Doped Organic Transistors.

Doping allows us to control the majority and minority charge carrier concentration in organic field-effect transistors. However, the precise mechanism of minority charge carrier generation and transport in organic semiconductors is largely unknown. Here, the injection of minority charge carriers into n-doped organic field-effect transistors is studied.

Antiferromagnetically Coupled Dimeric Dodecacopper Supramolecular Architectures of Macrocyclic Ligands with a Symmetrical μ6-BO3(3-) Central Moiety.

Reactions between 2,6-diformyl-4-alkyl(R)-phenol (R = CH3 or C(CH3)3) and 1,3-diamino-2-hydroxypropane (1,3-DAP) in the presence of copper(II) salts (Cu(BF4)2·6H2O, Cu(ClO4)2·6H2O/H3BO3/Ar) and triethylamine (TEA) in a single pot result in self-assembly of dimeric dodecacopper supramolecular architectures of 30-membered hexatopic macrocyclic ligands (H6L4 and H6L5) with unique and fascinating structures having the BO3(3-) anion as the central species bonded to all six copper centers in a symmetrical fashion (μ6-BO3(3-)). A number of closely related macrocyclic hexacopper complexes are reported: {[Cu6(L4)(μ6-BO3)(μ-H2O)(C3H7NO)2(BF4)][BF4]2·3C3H7NO}2 (1) (DMF = C3H7NO), {[Cu6(L4)(μ6-BO3)(μ-C3H7NO)3][ClO4]3·3C3H7NO}2 (2), {[Cu6(L5)(μ6-BO3)(μ-OH)(H2O)3(C3H7NO)][BF4]2·6C3H7NO·4C2H5OH·2H2O}2 (3), {[Cu6(L5)(μ6-BO3)(μ-CH3OH)(CH3OH)2][ClO4]3·10H2O}2 (4), and {[Cu6(L5)(μ6-BO3)(μ-CH3CO2)(μ-CH3O)(CH3OH)][BF4]·13CH3OH·8H2O}2 (5). A polymeric side product {[Cu2(H2L2)(CH3OH)(BF4)][BF4]}n (6), involving a 2 + 2 macrocyclic ligand, was also isolated and structurally characterized.

Oligonuclear Fe complexes (Fe, Fe4, Fe6, Fe9) derived from tritopic pyridine bis-hydrazone ligands-structural, magnetic, and Mössbauer studies.

Tri-topic pyridine bis-hydrazone ligands produce polynuclear complexes with Fe(II) and Fe(III) salts with varying nuclearity and metal ion oxidation states. Mononuclear, tetranuclear, hexanuclear, and nonanuclear examples are discussed using structural, magnetic and Mössbauer data. In one case, although X-ray data suggest a [3 × 3] Fe9 grid (space group P42/n), careful examination of the structure, in conjunction with magnetic and Mössbauer data, indicates an unusual situation where the corner and center sites are present at unit occupancy, whereas side site occupancy is ∼0.

Synthesis of a potential intermediate for TMC-95A via an organocatalyzed aldol reaction.

N-Prolinylanthranilamide-based pseudopeptide organocatalyst 14 was shown to promote enantioselective direct aldol reaction of 7-iodoisatin and 2,2-dimethyl-1,3-dioxan-5-one with 90% conversion (75% isolated yield), 90% enantioselectivity, and 23:1 diastereoselectivity. To demonstrate the synthetic utility of this chemistry, the racemic aldol reaction product was converted in five steps to a potential intermediate for construction of the natural product TMC-95A.

Polynuclear lanthanide (Ln) complexes of a tri-functional hydrazone ligand--mononuclear (Dy), dinuclear (Yb, Tm), tetranuclear (Gd), and hexanuclear (Gd, Dy, Tb) examples.

The lanthanide coordination chemistry of a tri-functional vanillin-hydrazone-oxime ligand reveals a variety of different products, depending on reaction conditions, with mono-nuclear (Dy), dinuclear (Yb, Tm), tetranuclear (Gd) and hexanuclear (Gd, Tb, Dy) examples. The Ln6 (Ln = Gd, Dy, Tb) complexes form in the presence of both triethylamine and acetic acid, and have unique, flat hexanuclear structures built on a μ3-O bridged triangular core, with the six lanthanide ions bridged further through μ-acetate and μ-Ohydrazone connections in an expanded fused triangular array. Similar reaction conditions with Yb(III) and Tm(III) lead preferentially to dinuclear systems, while in the presence of a competitive benzoate ligand a rectangular Gd4 complex results.

Tetranaphthyleno[5,6-bcd:11,12-b'c'd':17,18-b''c''d'':23,24-b'''c'''d''']tetrafuran.

The title compound, C(40)H(16)O(4) or [C(10)H(4)O](4), is a planar tetrameric cyclooligomer which crystallizes in the monoclinic space group P2(1)/n. The compound is located on an inversion center with the asymmetric unit consisting of half of the molecule. The compound displays an interesting packing structure, where the cyclooligomer displays both layered packing with respect to nearest neighbors and a rotation of adjacent planar rings that results in additional interactions.

Structures and magnetic properties of an antiferromagnetically coupled polymeric copper(II) complex and ferromagnetically coupled hexanuclear nickel(II) clusters.

Reactions between 2,6-diformyl-4-methylphenol (DFMF) and tris(hydroxymethyl) aminomethane (THMAM = H(3)L2) in the presence of copper(II) salts, CuX(2) (X = CH(3)CO(2)(-), BF(4)(-), ClO(4)(-), Cl(-), NO(3)(-)) and Ni(CH(3)CO(2))(2) or Ni(ClO(4))(2)/NaC(6)H(5)CO(2), sodium azide (NaN(3)), and triethylamine (TEA), in one pot self-assemble giving a coordination polymer consisting of repeating pentanuclear copper(II) clusters {[Cu(2)(H(5)L(2-))(μ-N(3))](2)[Cu(N(3))(4)]·2CH(3)OH}(n) (1) and hexanuclear Ni(II) complexes [Ni(6)(H(3)L1(-))(2)(HL2(2-))(2)(μ-N(3))(4)(CH(3)CO(2))(2)]·6C(3)H(7)NO·C(2)H(5)OH (2) and [Ni(6)(H(3)L1(-))(2)(HL2(2-))(2)(μ-N(3))(4)(C(6)H(5)CO(2))(2)]·3C(3)H(7)NO·3H(2)O·CH(3)OH (3). In 1, H(5)L(2-) and in 2 and 3 H(3)L1(-) and HL2(2-) represent doubly deprotonated, singly deprotonated, and doubly deprotonated Schiff-base ligands H(7)L and H(4)L1 and a tripodal ligand H(3)L2, respectively. 1 has a novel double-stranded ladder-like structure in which [Cu(N(3))(4)](2-) anions link single chains comprised of dinuclear cationic subunits [Cu(2)(H(5)L(2-))(μ-N(3))](+), forming a 3D structure of interconnected ladders through H bonding.

Stability and ring-shift tautomerization of cyclic anhydrides of benzenehexasulfonic acid.

Upon heating in a dry atmosphere, benzenehexasulfonic acid forms three cyclic anhydrides. Mono- and dianhydride do not hydrolyze readily due their flatter structures compared to the hydrolysis products. The trianhydride appears more to be reactive toward hydrolysis.

Bright, Red Single-Molecule Emitters: Synthesis and Properties of Environmentally Sensitive Dicyanomethylenedihydrofuran (DCDHF) Fluorophores with Bisaromatic Conjugation.

A group of new fluorescent dye materials for single-molecule imaging applications comprised of an amine donor, a π-system comprised of phenyl and thiophene rings and a 2-dicyanomethylene-3-cyano-2,5-dihydrofuran acceptor group have been synthesized. Relative to comparable single-ring compounds these doubly aromatic conjugated fluorophores have red-shifted absorption and emission usually accompanied by significantly increased quantum yields. Solvatochromism studies indicate that the photophysical properties of these dyes are sensitive to the solvent polarity and environmental rigidity.

1,1,3,3-Tetramethylguanidine solvated lanthanide aryloxides: pre-catalysts for intramolecular hydroalkoxylation.

The synthesis and structural characterization of six 1,1,3,3-tetramethylguanidine (H-TMG) solvated lanthanide aryloxide complexes are reported. Ln[N{Si(CH3)3}2]3 (Ln = Nd, La) was reacted with two equivalents of both H-TMG and HOAr {HOAr = HOC6H2(CMe3)2-2,6 (H-DBP) or HOC6H2(CMe3)2-2,6-CH3-4 (H-4MeDBP)} and one equivelent of ethanol (HOEt) to yield the corresponding [Nd(H-TMG)2(4MeDBP)2(OEt)] (1) and [La(H-TMG)2(DBP)2(OEt)] (2). Compounds 1 and 2 were further reacted with 4-pentyn-1-ol {HO(CH2)3C[triple bond]CH} to isolate [Nd(H-TMG)2(4MeDBP)2{O(CH2)3C[triple bond]CH}] (3) and [La(H-TMG)2(DBP)2{O(CH2)3C[triple bond]CH}] (4), respectively.

Synthesis and characterization of gold(III) complexes possessing 2,9-dialkylphenanthroline ligands: to bind or not to bind?

In an effort to discover potential alternatives to the anti-cancer drug cisplatin, the synthesis of gold(III) polypyridyl coordination complexes was pursued. Specifically, this report describes the synthesis and characterization of a series of 2,9-dialkyl-1,10-phenanthroline (Rphen) gold(III) coordination complexes (R = n-butyl, sec-butyl, and tert-butyl). Due to the steric hindrance imparted by the alkyl substituents, these ligands do not react with HAuCl4 to form square-planar gold(III) dichloride complex ions, as is the case with 1,10-phenanthroline, but instead form salts comprised of [AuCl(4)](-) anions and protonated 2,9-dialkylphenanthroline cations (compounds 1 and 2).

Self-assembly of mixed-valence Co(II/III) and Ni(II) clusters: azide-bridged 1D single chain coordination polymers comprised of tetranuclear units, tetranuclear Co(II/III) complexes, ferromagnetically coupled azide-bridged tetranuclear, and hexanuclear Ni(II) complexes: synthesis, structural, and magnetic properties.

One-pot reactions between 2,6-diformyl-4-methylphenol (DFMP) and 2-aminoethanol (AE) in the presence of cobalt(II) salts [Co(ClO4)2, CoCl2, Co(CH3CO2)2, Co(NO3)2] and sodium azide result in the self-assembly of novel one-dimensional single chain mixed-valence cobalt coordination polymers {[Co2(II)Co2(III) (HL)2(OCH3)2(N3)3]ClO(4).5H2O.CH3OH}n (1), {[Co2(II)Co2(III) (HL)2(OCH3)2(N3)3]Cl.

Synthesis, structure, and reactivity of low-coordinate 1,1,3,3-tetraethylguanidinate complexes.

Diethylcyanamide is added to a hexanes solution of lithium diethylamide [LiN(CH(2)CH(3))(2)] resulting in the formation of lithium 1,1,3,3-tetraethylguanidinate, [Li(mu-TEG)](6) (1). Upon successful isolation of 1, the metathesis reaction of MX(2) (MX(2) = MnBr(2), FeBr(2), CoBr(2), and ZnCl(2)) with [Li(mu-TEG)](6) and lithium bistrimethylsilylamide, LiN(SiMe(3))(2), was performed to generate dinuclear tetraethylguanidinate (TEG) complexes with the general formula [M(mu-TEG){N(SiMe(3))(2)}](2) {M = Mn (2), Fe (3), Co (4), Zn (5)}. Further reaction of 2 with 2 equiv of ethanol (EtOH) and 2 equiv of 2,6-ditert-butylphenol (H-DBP) results in the formation of the manganese alkoxide, [Mn(mu-OEt)(DBP)(H-TEG)](2) (6).

Synthetic, structural, and theoretical investigation of guanidinate complexes containing planar Cu(6) cores.

The addition of diethylcyanamide to a tetrahydrofuran solution of lithium dialkylamide LiN(CH(3))(2) or Li NCH(2)CH(2)CH(2) CH(2), Li(PYR), results in the corresponding lithium 1,1,3,3-tetraalkylguanidinate, Li(TAG). The subsequent metathesis reaction of Li(TAG) with CuCl generates hexanuclear copper(I) complexes with the general formula [Cu(mu-TAG)](6), where TAG = DEDMG (1) and DEPYRG (2).

Copper coordination polymers based on single-chain or sheet structures involving dinuclear and tetranuclear copper(II) units: synthesis, structures, and magnetostructural correlations.

Reactions between the potentially pentadentate (N(2)O(3)), trianionic double Schiff-base ligand 2,6-bis[[(2-hydroxyethyl)imino]methyl]-4-methylphenol (H(3)L) and Cu(CH(3)CO(2))(2) or Cu(ClO(4))(2), in the presence of NaN(3), give novel coordination polymers with chain {[Cu(2)(H(2)L)(N(3))(3)](2).H(2)O}(n) (1) or sheet [Cu(2)(H(2)L)(N(3))(3)](n) (2) and [Cu(2)(HL)(N(3))](n)[ClO(4)](n) (3) structures, respectively. These clusters are comprised of repeating dinuclear units (1) or their dimers (2 and 3).

Structurally characterized 1,1,3,3-tetramethylguanidine solvated magnesium aryloxide complexes: [Mg(mu-OEt)(DBP)(H-TMG)]2, [Mg(mu-OBc)(DBP)(H-TMG)]2, [Mg(mu-TMBA)(DBP)(H-TMG)]2, [Mg(mu-DPP)(DBP)(H-TMG)]2, [Mg(BMP)2(H-TMG)2], [Mg(O-2,6-Ph2C6H3)2 (H-TMG)2].

The synthesis and structural characterization of several 1,1,3,3-tetramethylguanidine (H-TMG) solvated magnesium aryloxide complexes are reported. Bu(2)Mg was successfully reacted with H-TMG, HOC(6)H(3)(CMe(3))(2)-2,6 (H-DBP), and either ethanol, a carboxylic acid, or diphenyl phosphate in a 1:1 ratio to yield the corresponding [Mg(mu-L)(DBP)(H-TMG)](2) where L = OCH(2)CH(3) (OEt, 1), O(2)CC(CH(3))(3) (OBc, 2), O(2)C(C(6)H(2)-2,4,6-(CH(3))(3)) (TMBA, 3), or O(2)P(OC(6)H(5))(2) (DPP, 4). Bu(2)Mg was also reacted with two equivalents of H-TMG and HOC(6)H(3)(CMe(3))-2-(CH(3))-6 (BMP) or HO-2,6-Ph(2)C(6)H(3) to yield [Mg(BMP)(2)(H-TMG)(2)] (5) and [Mg(O-2,6-Ph(2)C(6)H(3))(2)(H-TMG)(2)] (6).

Synthesis and characterization of group 11 1,1,3,3-tetraalkylguanidinate (TAG) clusters: [M2(mu-TAG){mu-N(SiMe3)2}]2 (M = Cu, Ag, and Au).

The addition of diethylcyanamide to a tetrahydrofuran solution of lithium dialkylamide {LiN(CH(3))(2) or LiN[upper bond 1 start]CH(2)CH(2)C[upper bond 1 end]H(2) CH(2), Li(PYR)} results in the corresponding lithium 1,1,3,3-tetraalkylguanidinate, Li(TAG). Two equivalents of Li(TAG) and 2 equiv of lithium bistrimethylsilylamide, LiN(SiMe(3))(2), were subsequently reacted with 4 equiv of Group 11 halide (CuCl, AgBr, and AuCl) to generate tetranuclear complexes with the general formula [M(2)(mu-TAG){mu-N(SiMe(3))(2)}](2) where M and TAG = {Cu, DEDMG, (1)}, {Ag, DEDMG, (2)}, {Au, DEDMG, (3)}, {Cu, DEPYRG, (4)}, {Ag, DEPYRG, (5)}, and {Au, DEPYRG, (6)}. Compounds 1-6 were characterized by single-crystal X-ray diffraction.

Stable ion and electrophilic chemistry of the sterically crowded stilbene 1,1'-Bi(benzocyclobutenylidene) and its derivatives.

Generation and NMR studies of novel carbocations and carboxonium ions are reported from sterically hindered stilbene 1,1'-bi(benzocyclobutenylidene) 1, its dimethoxy derivative 5, and from their skeletally rearranged derivatives, namely, the spirocyclic ketone 6, diastereomeric alcohols 7 and isomeric diols 8. Quenching experiments on the carbocations under various conditions resulted in the formation/isolation of several novel covalent adducts. Acid-catalyzed isomerization of the diols 8 produced a remarkable dimeric molecule, whose structure was confirmed by X-ray analysis.