Formation and Structure of Conjugated Salen‐Cross‐Linked Polymers and Their Application in Asymmetric Heterogeneous Catalysis

Abstract

A new type of cross-linked condensation polymer was obtained by the reaction of 1,3,5-tris[(5-tert-butyl-3-formyl-4-hydroxyphenyl)ethynyl]benzene (1) with ethylenediamine. Solid-state 13 C{ 1 H} CP/MAS NMR analysis showed that the polymer was pure and highly cross-linked and powder synchrotron X-ray diffraction indicated some degree of local structural order in the polymer. A chiral manganese−salenbridged polymer was obtained by the condensation of 1 with (1R,2R)-1,2-diphenyl-1,2-diaminoethane (3a) or (1R,2R)-1,2-

Covalent Interlinking of an Aldehyde and an Amine on a Au(111) Surface in Ultrahigh Vacuum

“…Similar salicylaldehyde-derived compounds are known to react in solution with amines to form imines. [12] The dialdehyde molecules adsorb with their backbones parallel to the substrate and form well-ordered structures of monomolecular height (Figure 1 a). [13] The molecular top- ography is typically dominated by bright protrusions at the ends of the molecules arising from the tert-butyl groups.…”

Surface Synthesis of 2D Branched Polymer Nanostructures

“…The herringbone reconstructed Au(111) (22 ffiffi ffi 3 p ) surface was prepared by argon-ion sputtering at 1.5 kV and annealing to 850 K. The trialdehyde (1,3,5-tris[(5-tert-butyl-3-formyl-4-hydroxyphenyl)ethynyl]benzene) [15] was vapor-deposited onto the substrate from a heated glass crucible. The 1,6-diaminohexane (> 99 %, Fluka) was dosed from a glass vial onto the substrate through a leak valve in an isolated reaction cell.…”

“…In solution the trialdehyde is known to form a cross-linked polymer by reaction with ethylenediamine. [15] Covalent interlinking of similar two-spoke salicylaldehydes and octylamine on Au-(111) under UHV conditions was recently demonstrated by STM and synchrotron-based X-ray spectroscopy. [16] STM images of the reactants adsorbed individually on the Au(111)-(22 ffiffi ffi 3 p ) surface are shown in Figure 1 b and c. Upon co-deposition followed by annealing above 400 K, open filamentous structures are formed (Figure 2 a).…”

“…Figure 1 a shows the investigated condensation polymerization reaction between an aromatic trisalicylaldehyde [14,15] (trialdehyde) and 1,6-diaminohexane (diamine), which results in a polymer connected by imine bonds. In solution the trialdehyde is known to form a cross-linked polymer by reaction with ethylenediamine.…”

“…In method B, the amines are supplied at a higher substrate temperature where the trialdehyde islands are partially dissolved and there are free diffusing trialdehydes. [15] The temperature is above the amine desorption temperature, but a low surface concentration of amines is maintained by adsorption-desorption equilibrium. Compared to method A, trialdehydes with one or more alkyl amines attached are therefore more likely to encounter and react with unreacted trialdehyde spokes before these are saturated by free diamines, thus leading to an increased connectivity.…”