Synergistic effects in clathrate selectivity

Abstract

The inclusion behaviour of a series of hydroxyl hosts with a variety of liquid guests has been investigated. The host 9-(4-methoxyphenyl)-9H-xanthen-9-ol (A1), C20H16O3, forms inclusion compounds with aniline (ANI), 3-picoline (3PIC), morpholine (MORPH), Nmethylacetamide (NMA) and N-methylformamide (NMF). Their structures have been elucidated and correlated with their thermal behaviour. The inclusion compounds A1ANI and A1MORPH were successfully solved in space group P21/c, whereas A13PIC was solved in 𝑃ī. Non-isothermal kinetics of desolvation were performed for A13PIC and A1MORPH. The packing of A13PIC and A1MORPH is characterized by (Host)(Guest) hydrogen bonds, whereas A1ANI is stabilised by (Host)(Host) hydrogen bonding. Three structures were obtained for the host A1 and the guest N-methylacetamide, with structural formulas of C20H16O3 C3H7NO (A1NMA), C20H16O3 2C3H7NO (A12NMA) and 2C20H16O3 2C3H7NO (2A12NMA). The packing of A1NMA, A12NMA and 2A12NMA are characterized by (Host)-OHO-(Guest) and (Guest)-NHO-(Guest) hydrogen bonds, which gave hydrogen bonding patterns of 𝐶2 2(7), 𝐶3 3(11) and 𝐶4 2(11) respectively. The hydrate A1NMFH2O was successfully solved in the triclinic space group 𝑃ī. The A1NMFH2O hydrogen bond pattern may be described according to Etter’s notation as 𝑅4 2(8) and 𝑅6 6(16). The host 9-(3-methoxyphenyl)-9H-xanthen-9-ol (A2), C20H16O3, forms inclusion compounds with morpholine (A2MORPH), N-methylacetamide (A2NMA) and N-methylformamide (A2NMF), with host-guest ratios 1:1. The crystal structure of the apohost was solved in Pbca with Z=8. The structures of A2MORPH and A2NMF were solved in 𝑃ī, whereas A2NMA was solved in P21/n. The packing of these structures is stabilised by (Host)(Guest) hydrogen bonds. The host 5-(4-methoxyphenyl)-5H-dibenzo[a,d]cyclohepten-5-ol (A26), C22H18O2, forms inclusion compounds with aniline (A26ANI) and morpholine (A26MORPH). A26MORPH and A26ANI crystallised in the space groups Pc and 𝑃ī respectively. The packing of these structures are characterized by (Host)-OHO-(Host) hydrogen bonding. A guest exchange reaction was performed. The host compounds 5-(4-chlorophenyl)-5H-dibenzo[a,d]cyclohepten-5-ol (C21H15OCl), 5-[3(trifluoromethyl)phenyl]-5H-dibenzo[a,d]cyclohepten-5-ol (C22H15OF3) and 5-(naphthalen-1-yl)-5H-dibenzo[a,d]cyclohepten-5-ol (C25H18O) form inclusion compounds with morpholine. All three structures were solved in 𝑃ī with the host molecules hydrogen bonded to the morpholine guests.