Pathway from Chain to Dimer in Cu(I) Camphor Hydrazone Complexes

Ag(I) camphor complexes: antimicrobial activity by design

Eleven new complexes of general formula [Ag(NO₃)(L-Y)₂] corresponding to Ag(I) camphorimine complexes [Ag(NO₃)(OC₁₀H₁₄NY)₂] (Y=NMe₂ (1); OH (2); C₆H₅ (3); 4-MeC₆H₄, (4); 3,5-(CH₃)₂C₆H₃ (5); 3-OHC₆H₄, (6); 3-ClC₆H₄ (7); 4-ClC₆H₄ (8); 4-FC₆H₄ (9); 4-CF₃C₆H₄ (10)) and the camphor sulfonylimine complex [Ag(NO₃)(O₂SNC₁₀H₁₄NY)₂] (Y=NH₂) were synthesized/characterized and their structural properties and antibacterial activity studied to gain insights into the structure-antimicrobial activity relationships. Five of the complexes were selected as representative examples and structures were optimized by Density Functional Theory calculations. The results show that the imine substituents (Y) at the camphor ligands drive the structure of the complexes from distorted octahedral to trigonal prismatic or linear ionic while the effect of the sulfonylimine ring does not appreciably affects the geometry of the complex. The lipophilicity and polarity which are important parameters concerning the biological activity of the complexes are also high dependent of the characteristics of the camphor ligands. The redox properties of the complexes studied by cyclic voltammetry showed that their reduction potentials are essentially independent of their electronic and steric properties. The antibacterial activity of all the complexes, against Gram-positive (S. aureus Newman) and Gram-negative (Escherichia coli ATCC25922, Pseudomonas aeruginosa 477, Burkholderia contaminans IST408) strains was evaluated through calculation of MIC values. Results show that complexes with camphor imine ligands (1-10) that combine high lipophilicity with low dipolar moment (3-5) exhibit enhanced antibacterial activity. The ability to establish hydrogen bonding emerged as an important contribution to the antibacterial activity of the camphor sulphonylimine complex 11 (Y=NH₂).

Efficient and Selective Methane Borylation Through Pore Size Tuning of Hybrid Porous Organic-Polymer-Based Iridium Catalysts

As a new energy source that could replace petroleum, the global reserves of methane hydrate (combustible ice) are estimated to be approximately 20 000 trillion cubic meters. A large amount of methane hydrate has been found under the seabed, but the transportation and storage of methane gas far from coastlines are technically unfeasible and expensive. The direct conversion of methane into value-added chemicals and liquid fuels is highly desirable but remains challenging. Herein, we prepare a series of iridium complexes based on porous polycarbazoles with high specific areas and good thermochemical stabilities. Through structure tuning we optimized their catalytic activities for the selective monoborylation of methane. One of these catalysts (CAL-3-Ir) can produce methyl boronic acid pinacol ester (CH₃ Bpin) in 29 % yield in 9 h with a turnover frequency (TOF) of approximately 14 h^-1 . Because its pore sizes favor monoborylated products, it has a high chemoselectivity for monoborylation (CH₃ Bpin:CH₂ (Bpin)₂ =16:1).

Structure and catalytic properties of novel copper isatin Schiff base complexes

Isatin Schiff bases in combination with copper ions act as non-innocent ligands amplifying the alcohol oxidation process.

Copper(i) complexes based on ligand systems with two different binding sites: synthesis, structures and reaction with O2

The synthesis of the ligand systems L1 and L2 with two different N₃-binding sites linked through a dibenzofuran spacer and their coordination properties towards a variety of Cu^I precursors are reported. The reaction of L1 with copper halides leads to the formation of a bimetallic species [(L1)(Cu^ICl)₂] (1), and metallodimers [((L1)(Cu^IX)₂)₂(μ-(Cu)(μ-X)₂)] (2: X = Br, 3: X = I) in which two dicopper complexes are bridged by a (μ-(Cu)(μ-X)₂)-moiety whereas L2 reacts with copper chloride to afford {[Cu(L2)Cl₂]}_n (8). Furthermore, starting from L1 in combination with copper(i) salts of weakly coordinating anions the dicopper complexes [(L1)(Cu^I(NCCH₃))₂](BF₄)₂ (4), [(L1)(Cu^I(NCCH₃))(Cu(Y))](Y) (5: Y = OTf, 6: Y = ClO₄) and [(L1)(Cu(dppe))](PF₆)₂ (7) were isolated, and employing L2, the complexes [(L2)(Cu^I(NCCH₃))₂](Z)₂ (9: Z = PF₆, 10: Z = OTf) and [(L2)(Cu(dppe))](PF₆)₂ (11) were obtained. Complexes 4-6 as well as 9 and 10 react rapidly with O₂ to form metastable O₂ adducts in acetone at -90 °C, where O₂ is bound between the two copper centers within one dicopper molecule, as evidenced by UV/Vis spectroscopy, kinetic investigations, Raman spectroscopy and studies with ligands containing the isolated donor sites. The reactivity of the O₂ adducts towards selected substrates was also investigated, showing their ability to act as electrophiles as well as nucleophiles.

A 3-D net based on weak metallophilic (Cu⋯Cu) interactions

The interconnection of 1-D [Cu(IN)] chains via weak metallophilic (Cu⋯Cu) interactions gives a 3-D network with photocatalytic properties.

Oxygen activation by copper camphor complexes

In situreduction of CuCl₂enables formation of Cu(i) complexes prone to activate molecular oxygen from air towards catalytic oxidation of 1,3-dicarbonyls.