Browsing by Author "Rowlands GJ"

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Anion Effects on the Structural and Magnetic Properties of a Series of Trinuclear CuII –LnIII –CuII Complexes
(American Chemical Society, 2025-11-04) Matheson BE; Dais TN; Donaldson ME; Takeshi S-I; Lyu L; Takano R; Ishida T; Rowlands GJ; Plieger PG
Two series of heterometallic CuII2LnIII complexes, ([Cu2Ln(H4L)2(MeOH)2Br](MeOH)4(Et2O)(Br2), where Ln = Y (1), Gd (2), Er (3), Tb (4)), and ([Cu2Ln(H4L)2(MeOH)2Cl2](MeOH)4(Et2O)Cl, where Ln = Y (5), Gd (6), Er (7), Tb (8), and H6L = (N,N′-bis(2,3,4-trihydroxybenzylidene)-1,2-phenylenediamine), were designed, synthesized, and characterized through X-ray and magnetic analyses. X-ray analysis revealed that the bromide containing complexes 1–4 possessed identical supramolecular arrangements, crystallizing in layers of 2D sheets, while chloride containing complexes 5–8 formed a 3D supramolecular lattice possessing an additional π–π stacking interaction per complex. DC magnetic susceptibility measurements showed that complexes 3 and 7 exhibited antiferromagnetic coupling between copper and erbium centers while the gadolinium (2 and 6) and terbium (4 and 8) containing complexes displayed ferromagnetic Cu─Ln coupling upon cooling. AC magnetic susceptibility measurements revealed that complexes 4 and 8 also displayed zero-field SMM behavior with Ueff = 17.8 and 16.0 K, respectively. The larger bromide anion in complex 4 aids in the isolation of the magnetic centers, resulting in a Ueff value higher than that of the chloride analogue.
Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro [2.2] metaparacyclophanes
(Beilstein-Institut, 2021) Patel S; Dais TN; Plieger PG; Rowlands GJ
Substituted [2.2]metaparacyclophanes are amongst the least studied of the simple cyclophanes. This is undoubtedly the result of the lengthy syntheses of these compounds. We report the simple synthesis of a rare example of a non-symmetric [2.2]metaparacyclophane. Treatment of [2.2]paracyclophane under standard nitration conditions gives a mixture of 4-nitro[2.2] paracyclophane, 4-hydroxy-5-nitro [2.2] metaparacyclophane and a cyclohexadienone cyclophane.
Correlated transcriptional responses provide insights into the synergy mechanisms of the furazolidone, vancomycin and sodium deoxycholate triple combination in Escherichia coli
(American Society for Microbiology, 2021-10-27) Olivera C; Cox MP; Rowlands GJ; Rakonjac J; Bradford PA
Effective therapeutic options are urgently needed to tackle antibiotic resistance. Furazolidone (FZ), vancomycin (VAN), and sodium deoxycholate (DOC) show promise as their combination can synergistically inhibit the growth of, and kill, multidrug-resistant Gram-negative bacteria that are classified as critical priority by the World Health Organization. Here, we investigated the mechanisms of action and synergy of this drug combination using a transcriptomics approach in the model bacterium Escherichia coli. We show that FZ and DOC elicit highly similar gene perturbations indicative of iron starvation, decreased respiration and metabolism, and translational stress. In contrast, VAN induced envelope stress responses, in agreement with its known role in peptidoglycan synthesis inhibition. FZ induces the SOS response consistent with its DNA-damaging effects, but we demonstrate that using FZ in combination with the other two compounds enables lower dosages and largely mitigates its mutagenic effects. Based on the gene expression changes identified, we propose a synergy mechanism where the combined effects of FZ, VAN, and DOC amplify damage to Gram-negative bacteria while simultaneously suppressing antibiotic resistance mechanisms. IMPORTANCE Synergistic antibiotic combinations are a promising alternative strategy for developing effective therapies for multidrug-resistant bacterial infections. The synergistic combination of the existing antibiotics nitrofurans and vancomycin with sodium deoxycholate shows promise in inhibiting and killing multidrug-resistant Gram-negative bacteria. We examined the mechanism of action and synergy of these three antibacterials and proposed a mechanistic basis for their synergy. Our results highlight much-needed mechanistic information necessary to advance this combination as a potential therapy.
Correlated Transcriptional Responses Provide Insights into the Synergy Mechanisms of the Furazolidone, Vancomycin, and Sodium Deoxycholate Triple Combination in Escherichia coli.
(27/10/2021) Olivera C; Cox MP; Rowlands GJ; Rakonjac J
Effective therapeutic options are urgently needed to tackle antibiotic resistance. Furazolidone (FZ), vancomycin (VAN), and sodium deoxycholate (DOC) show promise as their combination can synergistically inhibit the growth of, and kill, multidrug-resistant Gram-negative bacteria that are classified as critical priority by the World Health Organization. Here, we investigated the mechanisms of action and synergy of this drug combination using a transcriptomics approach in the model bacterium Escherichia coli. We show that FZ and DOC elicit highly similar gene perturbations indicative of iron starvation, decreased respiration and metabolism, and translational stress. In contrast, VAN induced envelope stress responses, in agreement with its known role in peptidoglycan synthesis inhibition. FZ induces the SOS response consistent with its DNA-damaging effects, but we demonstrate that using FZ in combination with the other two compounds enables lower dosages and largely mitigates its mutagenic effects. Based on the gene expression changes identified, we propose a synergy mechanism where the combined effects of FZ, VAN, and DOC amplify damage to Gram-negative bacteria while simultaneously suppressing antibiotic resistance mechanisms. IMPORTANCE Synergistic antibiotic combinations are a promising alternative strategy for developing effective therapies for multidrug-resistant bacterial infections. The synergistic combination of the existing antibiotics nitrofurans and vancomycin with sodium deoxycholate shows promise in inhibiting and killing multidrug-resistant Gram-negative bacteria. We examined the mechanism of action and synergy of these three antibacterials and proposed a mechanistic basis for their synergy. Our results highlight much-needed mechanistic information necessary to advance this combination as a potential therapy.
The concise synthesis and resolution of planar chiral [2.2]paracyclophane oxazolines by C-H activation
(Royal Society of Chemistry, 2022-03-17) Tewari S; Mungalpara MN; Patel S; Rowlands GJ
Planar chiral [2.2]paracyclophanes are resolved through the direct C-H arylation of enantiopure oxazolines, providing a convenient route to ligands and chiral materials. Preliminary results show that hydrolysis followed by decarboxylative phosphorylation leads to enantiopure [2.2]paracyclophane derivatives that are otherwise challenging to prepare.