Positional selectivity of reversible azomethine condensation reactions at solid/liquid interfaces leading to supramolecule formation

Abstract

We used in situ scanning tunneling microscopy to investigate the formation of two-dimensional supramolecules by means of reversible azomethine condensation reactions between aqueous 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and terephthaldicarboxaldehyde (TPA) or benzaldehyde (BA) at the solid/liquid interface of an iodine-modified Au(111) surface. A nanomesh and a close-packed array were formed by the reaction of TAPP with the dicarboxaldehyde. Formation of these structures was driven by Schiff base (azomethine) bonding and simultaneous self-assembly controlled by adsorption

Self-assembled π-conjugated macromolecular architectures — A soft solution process based on Schiff base coupling

“…Specifically, the use of aromatic primary amine and aromatic aldehyde units as complementary reactive substituents for aromatic Schiff base (also known as imine or azomethine) coupling. [49][50][51][52] The reaction between primary amines and aldehydes can be achieved spontaneously even in aqueous media at room temperature. The Schiff-base reaction has been widely applied for the synthesis of discrete supramolecules and 2-D [53] as well as 3-D nanoarchitectures.…”

“…8). [52] When the surface condensation reaction between TAPP and the monocarboxaldehyde (BA) was conducted on I/Au(111) in a solution containing TAPP and BA, the highly ordered close-packed arrays only consisted of a high-symmetry product, para TAPP-BA2. The high selectivity toward the reaction products was only achieved at the surfaces upon a supramolecular reaction, but not in homogeneous media.…”

Monomolecular covalent honeycomb nanosheets produced by surface-mediated polycondensation between 1,3,5-triamino benzene and benzene-1,3,5-tricarbox aldehyde on Au(111)

“…Previous reports have focused on the thermodynamic selfassembly of 2D covalent frameworks based on aromatic Schiff base (azomethine) coupling reactions. [34][35][36][37] The high reactivity and reversibility of the coupling reactions enable surfacemediated selective polycondensation and thermodynamic selfassembly in an ambient aqueous solution at room temperature, in a similar manner to the non-covalent systems based on hydrogen bonds 38,39 and halogen bonds. [40][41][42] The arrays of pconjugated linear polymers, porphyrin-based 2D mesh frameworks, and supramolecular arrangements of distinct molecular systems have been fabricated on iodine-modied Au(111) (I/ Au(111)).…”

Synthesis of Pyrene-Fused Pyrazaacenes on Metal Surfaces: Toward One-Dimensional Conjugated Nanostructures

“…On-surface organic synthesis has bloomed over the past decade. − Some of the most recent topical endeavors utilized azide–alkyne couplings, , couplings involving C–H activation of alkynes, alkenes, , and alkanes, , enediyne cyclizations followed by polymerization, as well as decarboxylative polymerization . In particular, Schiff base (imine) formations (Scheme a) have been successfully implemented for low-dimensional structures at solid–liquid interfaces. − Imine formation under these conditions has a dynamic character which relies on the reversibility of the relevant covalent bonds under thermodynamic control . Therefore, this type of bonding combines the increased stability of covalent bonds with the potential of producing regular superstructures.…”