Transition metal coordination polymers based on tetrabromoterephthalic and bis(imidazole) ligands: Syntheses, structures, topological analysis and photoluminescence properties

Diversifying molecular and topological space via a supramolecular solid-state synthesis: a purely organic mok net sustained by hydrogen bonds

“…The mok net 1a represents a rare family of entanglements that have only been realized in coordination polymers and metal-organic frameworks. For metal-organic materials, the metal centers and organic linkers are nodes and bridges, respectively, Gong et al, 2011;Liang et al, 2013;Zhang et al, 2015). O'Keeffe has pointed out that a single mok net can be considered difficult to achieve chemically given that one distance between two nodes is shorter than the distance between linked nodes.…”

“…A consequence of the self-catenation is the generation of two additional rings (six-and eight-membered, orange and purple, respectively). Importantly, the mok net has only been observed in assembly processes based on metal-organic components wherein the tetrahedral node is supplied by a metal center (Gong et al, 2011;Zhang et al, 2015;Liang et al, 2013). Moreover, the mok net has been recognized by O'Keeffe as 'likely to be difficult to achieve chemically' in the solid state due to its intricacy.…”

“…We show that the head-to-head (HH) cyclobutane 1a, following removal from the molecular template, self-assembles as a pure form to produce a hydrogen-bonded twofold interpenetrated net of mok topology. Within the network, the cyclobutane ring of 1a acts as a node with the radial phenolic and pyridyl groups serving as hydrogen-bond donor and acceptor linkers, respectively, resulting in the first purely organic mok network (Gong et al, 2011;Liang et al, 2013;Zhang et al, 2015;Li et al, 2017).…”

Organic fluorine in solid-state [2+2] photocycloadditions

“…259 Self-catenated framework structures, where the 'shortest rings' are being catenated by other 'shortest rings', represents a rare family of entanglements and only realized in CPs and MOFs. [254][255][256] Herein, we report a purely organic hydrogen-bond architecture featuring 2-fold interpenetration of the self-catenated 4connected mok nets ( Figure 115).…”

“…solid-state and protecting group strategy can effectively yield ever increasingly atypical structures. Solid-state supramolecular protecting group strategy (reprinted with permission, 252 © Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012)Here, we demonstrate a supramolecular protecting group strategy to selectively protect phenols for the purpose of synthesizing a cyclobutane that self-assembles to form a rare interpenetrated hydrogen-bonded net of mok topology [254][255][256]. The 4-c interpenetrated net is an unrealized network topology in crystal structures of organic networks.The photoproduct that results from the protecting strategy and sustains a hydrogenbonded framework based on a mok topology is rctt-1,2-bis(4-pyridyl)-3,4-bis(4phenolyl)cyclobutane (Pycb-OH).…”