Substituent-Controlled Tailoring of Chalcogen-Bonded Supramolecular Nanoribbons in the Solid State.

Nicolas Biot,Deborah Romito,Davide Bonifazi

doi:10.1021/acs.cgd.0c01318

Nicolas Biot, Deborah Romito + Show 1 more

Open Access

https://doi.org/10.1021/acs.cgd.0c01318

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Abstract

In this work, we design and synthesize supramolecular 2,5-substituted chalcogenazolo[5,4-β]pyridine (CGP) synthons arranging in supramolecular ribbons at the solid state. A careful choice of the combination of substituents at the 2- and 5-positions on the CGP scaffold is outlined to accomplish supramolecular materials by means of multiple hybrid interactions, comprising both chalcogen and hydrogen bonds. Depending on the steric and electronic properties of the substituents, different solid-state arrangements have been achieved. Among the different moieties on the 5-position, an oxazole unit has been incorporated on the Se- and Te-congeners by Pd-catalyzed cross-coupling reaction and a supramolecular ribbon-like organization was consistently obtained at the solid state.

Highlights

Crystal engineering has soared interest in the scientific community, given its valuable implications in the rational design of functional materials.[1−5] Several studies have focused on the use of supramolecular bonds, selectively involving recognition motifs to generate stable and predictable multidimensional networks in the solid state.[6−10] Among the several noncovalent interactions, hydrogen bonds embody the main interaction occurring in biological systems,[11,12] as well as being used for many applications in chemistry and materials science.[13−16] over the past decades, there has been a flourishing interest for a class of exotic noncovalent interactions, namely, Secondary Bonding Interactions (SBIs),[17] as attractive alternatives to the ubiquitous hydrogen bond in crystal engineering
When the central polarizable E atom belongs to Group VI of the periodic table, the term chalcogen bonding (EB, known as ChB) is used to describe the interaction between a positively polarized chalcogen atom and a Lewis base.[20−22] Despite recent developments in catalysis[23−28] and sensing,[25,29] EB interactions have been mainly exploited in crystal engineering,[30,31] providing a distinctive series of persistent recognition motifs.[32−35] The structure of the most part of these chalcogen-bonding synthons builds on a heterocyclic scaffold, in which the chalcogen bond donors and acceptors are proximal to each other,[36−38] effectively developing macrocyclic[39−41] and wire-like[42,43] supramolecular architectures
The synthesis started with the selective bromination of the commercially available amines 1Me and 1Cl using N-bromo succinimide (NBS) in MeCN, which provided compounds 2Me and 2Cl, respectively, in good and excellent yields

Summary

■ INTRODUCTION

Crystal engineering has soared interest in the scientific community, given its valuable implications in the rational design of functional materials.[1−5] Several studies have focused on the use of supramolecular bonds, selectively involving recognition motifs to generate stable and predictable multidimensional networks in the solid state.[6−10] Among the several noncovalent interactions, hydrogen bonds embody the main interaction occurring in biological systems,[11,12] as well as being used for many applications in chemistry and materials science.[13−16] over the past decades, there has been a flourishing interest for a class of exotic noncovalent interactions, namely, Secondary Bonding Interactions (SBIs),[17] as attractive alternatives to the ubiquitous hydrogen bond in crystal engineering. In contrast to chlorinated analogue Cl-Te-Ph, π−π stacking interactions govern the formation of columnar arrangements in a quasi-parallel head-to-tail fashion (estimated dπ−π = 3.542 Å), with I···π interactions (σ*-π, dC···I = 3.505 Å) bridging the columns (Figure 4f) Building on these observations, one can notice that wire-like structures are consistently attained over ribbon and dimeric arrangements with 5-functionalized CGP modules bearing a phenyl moiety in the 2-position. Te-congener Ox-TeCF3 develops HB/EB ribbons in the solid state These structures differentiate from those described so far because the O atom of the oxazole and the N atom of the pyridyl moiety both engage in two hydrogen bonds with the H atoms in positions 6 and 7 of a neighboring molecule (dO···C = 3.211 Å and dN···C = 3.423 Å, respectively).

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES