Multipoint Anchoring of the [2.2.2.2]Metacyclophane Motif to a Gold Surface via Self-Assembly: Coordination Chemistry of a Cyclic Tetraisocyanide Revisited

Abstract

A one-pot transformation of bis(2-isocyano-3-methylphenyl)ethane affords gram quantities of 8,16,24,32-tetraisocyano[2.2.2.2]metacyclophane ( 3). The solid state structure of 3 is remarkably close to the lowest energy conformation found on the potential energy landscape for 3 by DFT. In solution, the structure of metacyclophane 3 is mobile but can be locked in a rectangular gauche- anti- gauche- anti conformation by coordination of the isocyanide substituents to the [W(CO) 5] units to give [M] 4(mu 4-eta (1):eta (1):eta (1):eta (1)- 3) ( 5). The tetranuclear [M] 4(mu 4-eta (1):eta (1):eta (1):eta (1)- 3) motif featured in crystallographically characterized 5 may be present in several insoluble complexes of 3 previously described as mononuclear eta (4) species. A self-assembled monolayer of metacyclophane 3 is formed upon exposing a solution of 3 to the gold(111) surface with no precautions to exclude air or light. The monolayer nature of the film was confirmed by optical ellipsometry. The isocyanide stretching band for 3 shifts from 2119 cm (-1) in solution to 2175 cm (-1) upon chemisorption to metallic gold. The FTIR spectrum of the film indicates interaction of 3 with the gold surface via all four of its isocyanide anchors. No gold-facilitated oxidation of the -NC junctions was detected under ambient conditions. The energy cost associated with accessing the conformations of 3 suitable for mu 4-eta (1):eta (1):eta (1):eta (1) interaction of the molecule with the Au(111) surface is under 8 kcal/mol, a value that can be easily offset by formation of a gold-isocyanide bond. Two different mu 4-eta (1):eta (1):eta (1):eta (1) coordination arrangements of 3 with respect to gold atoms on the (111) face of the fcc Au lattice are suggested.

Engineered Nanostructures of Haptens Lead to Unexpected Formation of Membrane Nanotubes Connecting Rat Basophilic Leukemia Cells

“…(A) From the perspective of geometry only, the optimal arrangement of IgE-FcεRI complexes for degranulation. (B) AFM topographic image of DNP nanostructures produced using nanografting. − The periodicity of this DNP grid nanostructure is 39 ± 4 nm, and the edge-to-edge separation is 22 ± 5 nm . (C) From the perspective of geometry only, arrangements of IgE-FcεRI complexes for discouraging degranulation and facilitating nanotube formation.…”

Fourfold symmetric MCR's via the tetraisocyanide 1,3-diisocyano-2,2-bis(isocyanomethyl)propane

“…10,11,13 And, as far as reported, no successful fourfold IMCR was achieved with these tetraisocyanides. 10,11,13,14 Here, we report the synthesis, structure, and reactivity of the tetraisocyanide 1,3-diisocyano-2,2-bis(isocyanomethyl)-propane (1). Inspired by its symmetry and anticipating numerous unique applications, our goal was not only to synthesise and characterise this symmetrical tetraisocyanide 1 (Fig.…”