Synthesis of large generation poly(propyl ether imine) (PETIM) dendrimers

Large generation poly(propyl ether imine) (PETIM) dendrimers are synthesized in iterative synthetic cycles of two reductions and two Michael addition reactions. Dendrimers up to sixth generation, containing up to 128 peripheral functionalities, are synthesized. Growth of the PETIM dendrimers, possessing a tertiary amine as the branch juncture and an ether as the linker component, is assessed systematically by routine spectroscopic methods. The peripheries of these dendrimers possess either alcohols, amines, carboxylic acids, esters, or nitriles, thereby opening up possibilities for varied studies involving PETIM dendrimers

Synthesis of large generation poly(propyl ether imine) (PETIM) dendrimers

Large generation poly(propyl ether imine) (PETIM) dendrimers are synthesized in iterative synthetic cycles of two reductions and two Michael addition reactions. Dendrimers up to sixth generation, containing up to 128 peripheral functionalities, are synthesized. Growth of the PETIM dendrimers, possessing a tertiary amine as the branch juncture and an ether as the linker component, is assessed systematically by routine spectroscopic methods. The peripheries of these dendrimers possess either alcohols, amines, carboxylic acids, esters, or nitriles, thereby opening up possibilities for varied studies involving PETIM dendrimers

Increased Efficacies of an Individual Catalytic Site in Clustered Multivalent Dendritic Catalysts

In the studies reported so far on dendrimer-mediated catalysis, the efficacies of the catalytic units were studied and compared primarily across the generations. In order to identify the efficacy of an individual catalytic unit with respect to the number of such units present within a given generation, a series of catalysts were prepared within a generation. Dendrimers incorporated with phosphinemetal complexes were chosen for the study and as many as 11 catalysts within three generations were synthesized. The C-C bond-forming reactions, namely, the Heck and the Suzuki coupling reactions, were then selected to study the catalytic efficiencies of the series of partially and fully phosphine-metal complex functionalized dendrimers. The efficacies of the formation of cinnamate and biphenyl. catalyzed by the dendritic catalysts, were compared. The comparative analyses show that an individual catalytic site is far more effective in its catalytic activity when presented in multiple numbers, i.e., in a multivalent dendritic system, than as a single unit within the same generation, i.e., in a monovalent dendritic system. The study identifies the beneficial effects of the multivalent presentation of the catalytic moieties, both within and across the dendrimer generations

Selective Endo and Exo Binding of Mono- and Ditopic Ligands to a Rhomboidal Diporphyrin Prism

Copper(I) can preferentially form heteroleptic complexes containing two phosphine and two nitrogen donors due to steric factors. This preference was employed to direct the self-assembly of a porphyrin-faced rhomboidal prism having two parallel tetrakis(4-iminopyridyl)porphyrina- tozinc(II) faces linked by eight 1,4-bis(diphenylphosphino)- benzene pillars. The coordination preferences of the CuI ions and geometries of the ligands come together to generate a slipped-cofacial orientation of the porphyrinatozinc(II) faces. This orientation enables selective encapsulation of 3,3’- bipyridine (bipy), which bridges the ZnII ions of the parallel porphyrins, whereas 4,4’-bipy exhibits weaker external coordi- nation to the porphyrin faces. Reaction with 2,2’-bipy, by contrast, results in the displacement of the tetratopic porphyrin ligand and formation of [{(2,2’-bipy)CuI}2(diphosphine)2] . The differing strengths of interactions of bipyridine isomers with the system allows for a hierarchy to be deciphered, whereby 4,4’-bipy may be displaced by 3,3’-bipy, which in turn is displaced by 2,2’-bipy

Perspectives on dual-purpose functional nanomaterials for detecting and removing fluoride ion from environmental water

Fluoride (F–) is a unique analyte because when in small quantities, it is beneficial and harmful when in larger or negligible quantities, leaving it essential for dual-purpose detection and removal from a water sample to prevent fluoride-caused health risks. F– detection and removal using organic molecules and hybrid materials are extensively reported in the literature, but very few reports discuss dual-purpose detection and removal. Functional nanomaterials (FNM) based on nanoparticles, metal-organic frameworks, and carbon dots conjugated with fluorophore moiety are largely used for these purposes. Functional groups on nanomaterial surfaces exhibited various interactions such as agglomeration, electrostatic, hydrogen bonding, ion exchange, coordination and π-π stacking interactions, enabling dual-purpose detection and removal of F–. These materials offer unique properties such as tunable pore structure, size, and morphology coupled with large surface area and high thermal/chemical stability. Further, this perspective review discusses prospects for sustainable technologies and describes the advantages and disadvantages of using FNM based on its optical properties for detection and removal efficiency. We believe this is the first account that summarizes the single FNM that can be used for simultaneously the selective detection of F– in aqueous media and its efficient removal

First Cu-Nanostar as Sustainable Catalyst Realized through Synergistic Effects of Bowl-shaped Features and Surface Activation of Sporopollenin Exine

Recently, nanostar-shaped structures, including gold nanostars (NS), have drawn much attention for their potential use in surface-enhanced Raman spectroscopy (SERS) and catalysis. Yet, very few studies have been conducted on Cu-Au hybrid NS, and there are none for Cu-based NS. Herein, we describe an effective method for controlling copper oxide nanostar (ESP-PEI-CuI/IIO-NS) growth using sporopollenin as a sustainable template material. However, ESP-PEI-CuI/IIO-NS growth depends on sporopollenin surface functionalization. Sporopollenin surface activation was done by amine functionalization with polyethyleneimine (PEI), without which ESP-PEI-CuI/IIO-NS growth was not observed. The sporopollenin’s exine (outer wall) has bowl-like structures, which mediates the growth of Cu nanorods, resulting in an NS morphology. Furthermore, due to their increased surface area, ESP-PEI-CuI/IIO-NS showed excellent catalytic activity for Huisgen 1,3-dipolar cycloadditions even when used in H2O and without additives under greener conditions. This approach utilising biomass as a sustainable template would pave the way for developing controlled growth of nanostructures for SERS-related and catalytic applications

New Access to the Synthesis of 1,1,4,4-Tetracyanobuta-1,3-Diene-Based Push–pull Chromophores Using Tetracyanoethylene Oxide via [3+2] Cycloaddition-Ring Opening Reactions

Herein we report a new way to access the synthesis of established invaluable push–pull chromophores based on 1,1,4,4-tetracyanobuta-1,3-dienes (TCBDs) using tetracyanoethylene oxide (TCNEO) upon reaction with alkynes substituted with an electron-donating group (EDG) via [3+2] cycloaddition (CA) followed by ring-opening (RO) reactions. Further, we uncovered that the facile [3+2] CA–RO reaction under simpler reaction condition is possible due to the presence of EDG group, otherwise, even the formation of [3+2] cycloadduct without EDG requires harsher condition and does not lead to TCBD as reported earlier in 1965 by Linn and Benson

Synergistic Effects of Carbon Dots and Palladium Nanoparticles Enhances the Sonocatalytic Performance for Rhodamine B Degradation in the Absence of Light

Carbon dot (CD) and palladium nanoparticles (Pd NPs) composites are semiconducting materials having tremendous applications in catalysis with suitable bandgap. However, their combination with suitable polymer matrix in sono-photo-catalysis has not been explored. Herein, we have synthesized and characterized a new nano-hybrid catalyst from polyamide cross-linked CD-polymer and subsequent deposition of Pd NPs. Sonocatalytic activity of 99% rhodamine B dye-degradation was achieved in mere 5 minutes (min) under dark. Model catalyst replacing CD with benzene and other control studies revealed that synergistic effects of CD and Pd NPs enhances the sonocatalytic activity of nano-hybrid catalyst. Interestingly, visible light did not influence the activity significantly. While mechanistic investigations suggest that generation of reactive oxygen species on the surface of CD-polymer initiated by ultrasound which further facilitated by Pd NPs is the key for remarkable catalytic activity (rate constant 0.99 min-1). Recyclable heterogeneous catalyst under ambient conditions are promising for the utility of exploring sono-assisted dark-catalysis for several avenues

A Systematic Study to Unravel the Potential of using Polysaccharides based Organic Nanoparticles Versus Hybrid Nanoparticles for Pesticide Delivery

To daze conventional pesticide release limitations, nanotechnology-mediated pesticide delivery using natural polymers has been actively investigated. However, the lack of information on what are the beneficial/non-beneficial aspects of using hybrid- and organic- nanoparticles (NP) and among the polysaccharides which are better suited concerning pesticide loading efficiency (PLE wt%), entrapment efficiency (E.E %), and sustained-pesticide-release (SPR %) has prompted us to investigate this study. In this report, we systematically investigated a series of polysaccharides such as starch (S), cellulose (C), aminocellulose (AC), and sodium carboxymethylcellulose (NaCMC) coated on magnetite NP (MNP, Fe3O4) and complete organic nanocarrier systems (starch and cellulose) that have no MNP part were compared for the PLE wt% and SPR % efficiencies for chlorpyrifos (ChP) insecticide. Overall, all nanocarriers (NCs) have shown good to excellent PLE wt% due to the smaller-sized NP obtained through optimal conditions. However, among the hybrid polysaccharides studied, starch MNP (S-MNP) has shown a maximum PLE of 111 wt% in comparison with other polysaccharides (80 – 94 wt%) coated hybrid-NCs as well as with organic-NCs (81 – 87 wt%). The use of inorganic support does improve the PLE wt% markedly for starch but not for cellulose derivatives. Similarly, the SPR results of S-NP showed a remarkably better sustained-release profile for ChP of 88 % in 14 days. In contrast, other unfunctionalized and functionalized celluloses exhibited poor release profiles of 60 – 20 % for the same period. This study may help the researchers choose the right system for designing and achieving enhanced pesticide efficiency

Unravelling the effect of non-drug spacers on a true drug-polymer and a comparative study of their antimicrobial activity

Several studies have been conducted on polymerisation of drug units using spacers or other polymeric units. In order to study the importance of spacers in drug polymers, we designed polymers with and without spacers. As a proof of concept, herein, we present a comparative study on the efficacy of antibacterial activity using a polymeric biocide (PB) C0P1 having no spacer (0%) and two other PBs with varied spacer content (C2P2:29%, C10P3:53%). We considered C0P1 as a potential new type of PB generated from a widely used fluoroquinolone antibiotic, ciprofloxacin 1, by a simple self-condensation activation with thionyl chloride. Monomer 2 (formylated methyl ester of 1) was polymerised with ethylenediamine (C2) and 1,10-diaminodecane (C10) to provide C2P2 and C10P3, respectively. The trend for minimum inhibitory concentration study against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was observed as 1>C0P1>C2P2=C10P3>>2. Further, after coating on nylon threads, the non-spacer polymer C0P1 showed enhanced zone of inhibition (ZOI) than monomer 1 as well as the spacer polymers owing to its superior coating ability and sustained drug release capabilities. Thus, this study clearly states that the bio-efficacy of a drug-polymer could be retained and enhanced in the absence of non-bioactive spacer units