Article pubs.acs.org/crystal
Enhanced Stability toward Humidity in a Family of Hybrid Ultramicroporous Materials Incorporating Cr2O72− Pillars Hayley S. Scott, Mohana Shivanna, Alankriti Bajpai, Kai-Jie Chen, David G. Madden, John J. Perry IV, and Michael J. Zaworotko* Bernal Institute, Department of Chemical Sciences, University of Limerick, Limerick, Republic of Ireland S Supporting Information *
ABSTRACT: Dichromate (Cr2O72−) pillared pcu hybrid ultramicroporous materials, while previously shown to exhibit benchmark selectivity for small polarizable gases, sometimes suffer from poor stability when exposed to moisture, which could limit their potential application in gas separation systems. In attempting to improve their stability toward humidity, we have crystal engineered two new families of DICRO-L-M-i materials of formula [M(L)2(Cr2O7)]n (M = Ni2+, Co2+; L = 5: 1,4-bis(4-pyridyl)xylene; 6: 1,4-bis(4-pyridyl)durene). Evaluating these materials in combination with a previously reported analogue, DICRO-4-Ni-i, in terms of their stability toward humidity has revealed a relationship between increasing the number of methyl groups on the dipyridyl organic linkers and a greater stability toward humidity.
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INTRODUCTION Crystal engineering,1 which describes how molecular structure influences crystal structure and physicochemical properties, has progressed to such a point that rational design strategies can be employed for the synthesis of new families of crystalline materials with desired functional properties. Metal−organic materials (MOMs),2 including porous coordination polymers3 or metal−organic frameworks,4 represent a broad class of materials amenable to the principles of crystal engineering. Recently we have defined a subclass of MOMs combining two essential features: the incorporation of strong electrostatics, perhaps in the form of inorganic anions with electronegative atoms, and ultramicropores (
