Supramolecular
assembly utilizing simultaneous formation of three
pnictogen bonds around a single antimony vertex was explored via X-ray
crystallography, solution NMR, and computational chemistry. An arylethynyl
(AE) ligand was designed to complement the three electrophilic regions
around the Sb compound. Though solution studies reveal large binding
constants for individual pyridyl units with the Sb donor, the rigidity
and prearrangement of the AE acceptor proved necessary to achieve
simultaneous binding of three acceptors to the Sb-centered pnictogen-bond
donor. Calculations and X-ray structures suggest that negative cooperativity
upon sequential binding of three acceptors to a Sb center limits the
utility of triple-pnictogen bonding pyridyl acceptors. These limitations
can be negated, however, when positive cooperativity is designed into
a complementary acceptor ligand.
Antimony(III) alkoxide cages were designed as building blocks for predictable supramolecular self-assembly. Supramolecular synthons featuring two Sb···O secondary bonding interactions (SBIs), each SBI stronger than 30 kJ/mol, were used to drive the formation of the supramolecular architectures. Judicious choice of pendant groups provided predictable control over the formation of self-assembled 3D columnar helices, which crystallized with hollow morphologies, or a self-assembled 2D bilayer. The Sb-O stretching frequency provides a spectroscopic signature of Sb···O SBI formation.
Artificial vesicles can aid in the study and understanding of biological cell membranes. This study employs pnictogen bonding to actively direct the self-assembly of a true reversed bilayer. Antimony(iii) alkoxide cages that self-assemble through multiple strong SbO interactions propagate in two dimensions to form a reverse bilayer structure in the solid state. Long alkyl tails allow these reverse bilayers to be processed into vesicles in solution that are a reverse of biological cell membranes.
Triple pnictogen bonding refers to the ability of a pnictogen atom to engage in three simultaneous pnictogen bonds (PnBs) to a complementary partner through a single pnictogen atom. This supramolecular strategy was recently introduced as a unique facet of pnictogen bonding as compared to other named supramolecular interactions. Here, the ability of bismuth to participate in this phenomenon is demonstrated using Bi((NC 9 H 7 ) 3 CH 3 ). The study reveals that Bi engages in stronger PnBs than the analogous Sb system. The results have been contrasted with Bi systems that form strong coordination bonds, and analysis of the electron density along the bond path reveals key differences. The solution behavior of these newly synthesized supramolecules were studied by PFGSE NMR spectroscopy and they are found to remain intact in solution. Molecular design strategies that allow for triple pnictogen bonding should find use in the fields of molecular recognition and crystal engineering.
Photovoltaic characteristics of flexible graphene/Ag electrode – based polymer solar cells as a function of electrode thickness under bending deformation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.