Control of Interpenetration in Two-Dimensional Metal−Organic Frameworks by Modification of Hydrogen Bonding Capability of the Organic Bridging Subunits Masoumeh Servati-Gargari, † Ghodrat Mahmoudi,* ,† Stuart R. Batten,* ,‡,§ Vladimir Stilinovic ́ ,* ,∥ Derek Butler, ⊥ Laurance Beauvais, ⊥ William Scott Kassel, # William G. Dougherty, # and Donald VanDerveer ○ † Young Researchers and Elite Club, Tabriz Branch, Islamic Azad University, Tabriz, Iran ‡ School of Chemistry, Monash University, Victoria 3800, Australia § Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia ∥ Department of Chemistry, Faculty of Science, University of Zagreb, HR-10000 Zagreb, Croatia ⊥ Department of Chemistry San Diego State University San Diego, California 92182-1030, United States # Department of Chemistry, Villanova University, 215 Mendel Science Center, Villanova, Pennsylvania 19085, United States ○ Department of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States * S Supporting Information ABSTRACT: Six coordination polymers were prepared by linking Mn(SCN) 2 units by three different bis(4-pyridyl) substituited hydrazone derivatives (L) in three different solvents (methanol, ethanol, and acetonitrile) in order to study the effect of the hydrogen bonding ability of L on the formation of solvates rather than interpenetrated solvent-free interpenetrated structures. When the ligand L which cannot act as a hydrogen donor was used, in all three solvents the same product was obtained. This was a [Mn(SCN) 2 L 2 ] n metal− organic framework, consisting of two-dimensional (2D) networks, each interpenetrating two neighboring ones. When the bridging ligands L have additional functional groups capable of acting as hydrogen donors or acceptors, synthesis from acetonitrile yields non-interpenetrating 2D [Mn(SCN) 2 L 2 ] n networks with solvent molecules occupying the voids of the network. Other solvents were found to yield interpenetrated solvent free networks, or they replaced some of the L ligands, forming one-dimensional coordination polymers. 1. INTRODUCTION The research of synthesis and properties of metal−organic frameworks (MOFs) is among the most rapidly developing areas in materials chemistry today 1−11 due to their potential as functional materials in gas storage and separation, 12−17 catalysis, 18−21 as chemical sensors, 22−24 in drug delivery, 25,26 and many others. Most of these potential and actual applications are based on the high and permanent porosity of these materials, with pore sizes ranging from several angstroms to over 10 nm, which in turn also leads to high specific surfaces and high absorptivity. However, structures with large voids are inherently unstable, and upon their formation, the porosity of the system is often reduced by interpenetration of one (or several) frameworks through another. 27−36 Such interpene- trated structures are polymeric analogues of catenanes and rotaxanesalthough there is no covalent bonding between the interpenetrated networks, they cannot be separated without the destruction of the entire network. An alternative way a structure with large voids is stabilized is by the inclusion of solvent molecules. In such materials, the solvent can often be subsequently removed or replaced, rendering them functional porous materials. A key question in the design of functional MOFs is therefore the one of controlling (or avoiding) the formation of interpenetrated structures. 37,38 There are a number of methods that have shown some success in suppressing the inter- penetration in MOFs, and these include modification of reaction conditions, 39−41 the use of templates, 42−54 use of flexible ligands, 55 and modification of ligands. 56−65 The latter approach has for the most part been based on the use of ligands with bulky substituents, as such substituents that can fill the voids of the structure thus both stabilizing the structure by Received: November 29, 2014 Revised: January 30, 2015 Published: February 9, 2015 Article pubs.acs.org/crystal © 2015 American Chemical Society 1336 DOI: 10.1021/cg501741r Cryst. Growth Des. 2015, 15, 1336−1343