Shifting the Triangle–Square Equilibrium of Self-Assembled Metallocycles by Guest Binding with Enhanced Photosensitization

Abstract

Shifting a triangle−square equilibrium in one direction is an important problem in supramolecular self-assembly. Reaction of a benzothiadiazole-based diimidazole donor with a cis-Pt(II) acceptor yielded an equilibrium mixture of a triangle ( [ C 1 8 H 2 4 N 1 0 O 6 S 1 P t 1 ] 3 ≡ P t M C T ) a n d a s q u a r e ([C 18 H 24 N 10 O 6 S 1 Pt 1 ] 4 ≡ PtMC S ). We report here the shifting of such equilibrium toward a triangle using a guest (pyrene aldehyde, G1). While both benzothiadiazole and pyrene aldehyde can form reactive oxygen species (ROS) in organic solvents, their therapeutic use in water is restricted due to aqueous insolubility. The enhanced water solubility of the benzothiadiazole unit and G1 by macrocycle formation and host−guest complexation, respectively, enabled enhanced ROS generation by the host−guest complex (G1′ ⊂ PtMC T ) in water (G1′ = hydrated form of G1). The guestencapsulated metallacycle (G1′ ⊂ PtMC T ) has shown synergistic antibacterial activity compared to the mixture of macrocycles upon white-light irradiation due to enhanced ROS generation. The mechanism for such enhanced activity was established by measuring the oxidative stress and relative internalization of PtMCs and G1′ ⊂ PtMC T .

Bifunctional Role of Methyl Viologen in UV and X-ray Sensitive Switchable Organophosphonate Single Crystal

“…Besides, the high temperature SCXRD experiment was also conducted to confirm the absence of a thermochromic effect into the present system (Table S2). − Importantly, the enhancements of two closer O···N distance were alleged throughout the framework after longer time irradiation of X-ray, and the highest enlargement of O···N distance was found to be 3.5109 (7) Å for templated MV 2+ ion and 3.5525(5) Å for coordinated MV + ion in NIT1B (Figure S9, Supporting Information). The major enlargement occurred along the c axis after X-ray irradiation on NIT1 crystal, that can be seen by comparing the N–C bond length (pyridinium N and methyl C) of coordinated methyl viologen moiety (from 1.4809(1) to 1.4856(1) Å) (Figure S9, S11 and Table S4–S7 in ESI).…”

Ligand-Mediated Exfoliation and Antibacterial Activity of 2H Transition-Metal Dichalcogenides

“…After this, all solutions were incubated at 37 °C while wrapping with the aluminum foil to avoid photochemical oxidation. From the stock, 100 mL of the solution ifferrent intervals of time (15,30,60, and 120 min) was added to 100 mL of 2 mM DTNB (SRL Chem) in 50 mM Tris-HCl (pH 8.3, SRL Chem) buffer taken in a 96-well plate. Then, the GSH loss was estimated by measuring the absorbance at 412 nm.…”

“…Hence, there is an emergency call to the researchers to develop new-generation antibiotics which can escape the resistance pathway. 29,30 Nanomaterials are the alternative approach for this because of their multimodal attacks against the bacteria. 31 Among nanomaterials, two-dimensional (2D) nanomaterials can offer added advantages due to their high surface area-to-volume ratio, sharp edges, and basal plane interactions.…”

“…Hence, we hypothesized that the thiol ligand can be used to functionalize other TMDs due to their sulfur or selenium defect since functionalized TMDs have prominent importance in biological applications such as drug-delivery agents, sensing, NIR photothermal agent, peroxidase activity, and disinfection. − Recently, bacterial infection has caused a surge in patients’ death because of their growing resistance toward conventional antibiotics. Hence, there is an emergency call to the researchers to develop new-generation antibiotics which can escape the resistance pathway. , Nanomaterials are the alternative approach for this because of their multimodal attacks against the bacteria . Among nanomaterials, two-dimensional (2D) nanomaterials can offer added advantages due to their high surface area-to-volume ratio, sharp edges, and basal plane interactions. ,− It has been reported earlier from our group that functionalized MoS 2 shows enhanced antibacterial activity .…”

Water-Soluble Pd6L3 Molecular Bowl for Separation of Phenanthrene from a Mixture of Isomeric Aromatic Hydrocarbons

“…Solid-phase extraction and liquid–liquid extraction are commonly used techniques for the extraction of a wide variety of PAHs . However, these conventional techniques suffer from many drawbacks, such as time-consuming multiple steps, poor reproducibility, and the requirement for large amounts of samples. , Inspired by natural host–guest systems, a wide variety of artificial hosts have been proposed as efficient alternatives to the classical extraction and purification techniques to overcome the above-mentioned drawbacks. ,− Among the potential artificial hosts for separation applications, self-assembled discrete molecular architectures have gained special attention due to their easy accessibility in quantitative yields. ,− In fact, continuous efforts have been made to synthesize self-assembled coordination architectures for guest encapsulation, catalysis, sensing, light harvesting, stabilization of reactive species, drug delivery, and separation. , Separation of target molecules using water-soluble hosts is of enormous interest both from an industrial and an environmental point-of-view because they offer the possibility of a simple separation technique at ambient conditions. ,, Coordination-driven self-assembly involving metals is an efficient method for designing such water-soluble hosts. Symmetrical ligands have been widely used for such coordination-driven self-assembly due to their selective confluence toward discrete assemblies.…”