Selected Tricyclic Fused Systems: Host Behavior in the Presence of Mixed Xylenes and Ethylbenzene

Abstract

Two tricyclic fused host systems, namely, N,N′-bis­(5-phenyl-5-dibenzo­[a,d]­cycloheptenyl)­ethylenediamine H1 and N,N′-bis­(5-phenyl-10,11-dihydro-5-dibenzo­[a,d]­cycloheptenyl)­ethylenediamine H2, were investigated for their selectivity behavior in xylene isomer (o-Xy, m-Xy, p-Xy) and ethylbenzene (EB) mixtures. H1 only formed a complex with p-Xy, and H2 only with o-Xy, in single solvent recrystallization experiments. When H1 and H2 were recrystallized from equimolar mixtures of every combination of the four organic solvents, contrasting host selectivities were observed: H1 favored p-Xy and H2 favored o-Xy. High selectivities for p-Xy (87.2–88.7%) were noted in equimolar binary experiments with H1, while H2 furnished crystals with 91.3% o-Xy from an o-Xy/p-Xy mixture. Remarkably, only the apohost was recovered when p-Xy or o-Xy (for H1 or H2) was absent from the mixtures. Constructed selectivity profiles affirmed observations from these equimolar experiments. Thermal analyses demonstrated that H1 ·p-Xy was significantly less stable than H2 ·o-Xy, and SCXRD analyses explained these observations: p-Xy, in its complex with H1, was accommodated in wide open channels and did not experience any noncovalent interactions with the host molecule; on the other hand, o-Xy in H2 was bound tightly in near-discrete cages and, furthermore, interacted with H2. Both host compounds demonstrated the ability to separate various of the mixtures reported in this work.

Host behaviour of two tricyclic fused systems in mixed anisole guest solvents

“…17,18 The two tricyclic-fused host systems, N,N′-bis(5-phenyl-5-dibenzo[a,d]cycloheptenyl)ethylenediamine H1 and its 10,11-dihydro analogue N,N′-bis(5-phenyl-10,11-dihydro-5dibenzo[a,d]cycloheptenyl)ethylenediamine H2 (Scheme 1), have been used with tremendous effect for the separation of various mixtures containing the xylenes (o-Xy, m-Xy and p-Xy) and/or ethylbenzene. 19 In that work, H1 and H2 possessed significant selectivities for p-Xy and o-Xy, respectively. These host compounds, while having the ability to form inclusion compounds with a wide variety of guest species, were found also to have an affinity for small dihalogenated alkanes.…”

Evaluation of the Behavior of Two Tricyclic-Fused Host Systems in the Presence of Single and Mixed Isomers of the C8H10 Aromatic Crude Oil Fraction

“…14 For example, recently, tricyclic fused systems with sevenmembered B rings have demonstrated remarkable separation potential for various mixtures of xylenes and EB. 15 It was reported that, more specifically, N,N′-bis(5-phenyl-5-dibenzo-[a,d]cycloheptenyl)ethylenediamine and its 10,11-dihydro analogue, N,N′-bis (5-phenyl-10,11-dihydro-5-dibenzo[a,d]cycloheptenyl)ethylenediamine, possessed an overwhelming preference for pXy and oXy, respectively, when presented with such mixtures. Furthermore, other tricyclic fused systems based on the xanthenyl and thioxanthenyl systems have demonstrated selectivity behavior in such mixtures, favoring either pXy or oXy, dependent upon the molecular structure of the host compound employed.…”

“…Another important use of this field of science is in the separation of isomers . For example, recently, tricyclic fused systems with seven-membered B rings have demonstrated remarkable separation potential for various mixtures of xylenes and EB . It was reported that, more specifically, N , N ′-bis­(5-phenyl-5-dibenzo­[ a , d ]­cycloheptenyl)­ethylenediamine and its 10,11-dihydro analogue, N , N ′-bis­(5-phenyl-10,11-dihydro-5-dibenzo­[ a , d ]­cycloheptenyl)­ethylenediamine, possessed an overwhelming preference for p Xy and o Xy, respectively, when presented with such mixtures.…”