Controlling Topology within Halogen-Bonded Networks by Varying the Regiochemistry of the Cyclobutane-Based Nodes.

Taylor J Dunning,Daniel K Unruh,Eric Bosch,Ryan H Groeneman

doi:10.3390/molecules26113152

Taylor J Dunning, Daniel K Unruh + Show 2 more

Open Access

https://doi.org/10.3390/molecules26113152

Copy DOI

Abstract

The formation of a pair of extended networks sustained by halogen bonds based upon two regioisomers of a photoproduct, namely rctt-1,3-bis(4-pyridyl)-2,4-bis(phenyl)cyclobutane (ht-PP) and rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (hh-PP), that have varied topology is reported. These networks are held together via I⋯N halogen bonds between the photoproduct and the halogen-bond donor 1,4-diiodoperchlorobenzene (C6I2Cl4). The observed topology in each solid is controlled by the regiochemical position of the halogen-bond accepting 4-pyridyl group. This paper demonstrates the ability to vary the topology of molecular networks by altering the position of the halogen bond acceptor within the cyclobutane-based node.

Highlights

Varying the Regiochemistry of the Halogen bonding, the interaction between an electrophilic region on a halogen atom within a molecule and a nucleophilic region on a different atom, is a well-established and recognized non-covalent interaction [1]
The photoproduct rctt-tetrakis(4-pyridyl)cyclobutane (TPCB) has been shown to act as a four-connecting node in the formation of different multi-dimensional extended molecular solids based upon halogen bonding interactions [5,6]
We have recently demonstrated that C6 I2 Cl4 is a reliable I· · · N halogen-bond donor that participates in face-to-face π· · · π stacking, thereby aligning alkene-based reactant molecules to undergo a [2 + 2] photoreaction in the organic solid state [8,10]

Summary

Introduction

Varying the Regiochemistry of the Halogen bonding, the interaction between an electrophilic region on a halogen atom within a molecule and a nucleophilic region on a different atom, is a well-established and recognized non-covalent interaction [1]. Halogen bonding interactions have been one of the main driving forces in the formation of numerous organic solids [2,3]. The formation of extended molecular networks held together by these interactions continues to be an active area of research for crystal engineers. The careful selection of both the node and the linker is critical in the overall design of the framework along with the desired topology [4]. The incorporation of nodes based upon cyclobutane photoproducts, generated in the solid state via the [2 + 2] cycloaddition reaction, continues to yield diverse molecular solids. The photoproduct rctt-tetrakis(4-pyridyl)cyclobutane (TPCB) has been shown to act as a four-connecting node in the formation of different multi-dimensional extended molecular solids based upon halogen bonding interactions [5,6]

Methods

Results

Conclusion