Synthetic ionophores. Part 18: Ag+ selective trithiabenzena- and dithiabenzenapyridinacyclophanes 1

Abstract

The phase transfer catalysed nucleophilic displacement of 1,3-bis(bromomethyl)benzene, 2-methoxy-5methyl-1,3-bis(bromomethyl)benzene (2) and 1,4-bis(bromomethyl)benzene with 2-mercaptoethanol gives the respective diols 3, 4 and 12 (80-85%), which undergo intermolecular cyclodehydrochlorination with thiodiglycolyl dichloride and pyridine-2,6-dicarbonyl dichlorideؒHCl to provide m-phenylene (7-10) and p-phenylene (13-14) based crownophanes. The single crystal X-ray structures of crownophanes 8 and 13 and their NMR studies show that the m-phenylene and p-phenylene rings remain in plane and perpendicular to the macrocyclic ring both in solution and solid phases. These crownophanes offer three soft coordinating sites (3 × S or 2 × S and 1 N) conducive to complexation with Ag ϩ and the steric restrictions imposed by m-and p-phenylene rings restrict 2 : 1 (L : M) sandwich complexation required for complexation with the borderline soft Pb 2؉ cation. The crownophanes 7 and 9 extract Ag ؉ 172 and 602 times, respectively, more than Pb 2؉ . Conformational analysisThe X-ray crystal structure of crownophane 8 (Fig. 1, Table 1) shows that the m-phenylene ring remains in the mean plane of the macrocyclic ring. The substituent O᎐Me seems to play a dominant role in determining the conformation of the macroring. The bond O5᎐C18 is almost perpendicular to the phenylene ring (C11᎐C16᎐O5᎐C18 being 96.7Њ). The torsion angle S2᎐C10᎐C11᎐C16 is 86.2(3)Њ and consequently both S2᎐C10 and C18᎐O5 bonds point towards the same side with respect to the phenylene ring (Fig. 1). To avoid steric crowding the S1᎐C1 bond points in a direction opposite to the C18᎐O5 bond, the torsion angle C16᎐C15᎐C1᎐S1 being 97.8(3)Њ. The torsion angle studies indicate that out of the four possible 1,4-thiaoxa units (O᎐CH 2 ᎐CH 2 ᎐S), three are antiperiplanar [torsion angles 173.8(2)-177.1(2)Њ], whereas the fourth one (O4᎐C8᎐C9᎐S3) is synclinal [59.7(3)Њ] about the C᎐C bond. The torsion angles about the C᎐O bond are antiperiplanar and about the C᎐S bond they are synclinal with the exception of C9᎐S2᎐C10᎐C11 which is antiperiplanar. In the segments O1᎐C4᎐O2 and O3᎐C7᎐O4, the carbonyl oxygens O2 and O4 point towards opposite sides of the macro-ring mean plane. The major difference in the conformation angles in the two halves of the macroring is that torsion angle C2᎐S1᎐C1᎐C15 is synclinal whereas

3,11,19‐Trithia[3.3.3]pyridinophane: Structural Diversity in Its Transition Metal Complexes

“…The complexing abilities of the macrocycle 10 with the selected metal cations Ag I , Cd II , Cu II , Co II , Hg II , Ni II , Pb II and Zn II were assessed by solvent extraction of the metal chlorides from aqueous solutions into chloroform. The procedure was based on the method used by Kumar et al and Nishimura et al, in their investigation of mixed nitrogen and sulfur/oxygen‐donor cyclophanes 51,52. The extraction results, presented in Table 3, indicate that the macrocycle has poor selectivity and it extracts all the metals appreciably.…”

Crystal structure of 6-ethylidene-4-vinyl-18,21-dioxa-15,24-dithia-2,5,8- triazatricyclo[23.4.0.0]nonacosa-1(25),4,9,11,13,26,28-heptaene-3,7-dione, C25H25N3O4S2, a 21-membered dioxa-dithia-diamide based macrocycle

“…During our studies on the development of silver selective ionophores, it has been found that the title compound does both, extracts and transports Ag + picrate selectively than Pb 2+ and other metal ions [sel.ext (Ag + /Pb 2+ ) = 564, sel.^nsp (Ag + /Pb 2+ ) = 80] [7][8][9][10]. Its 1 C-NMR spectrum shows more than one signal for each C atom, it may exist as a mixture of two isomeric structures or may have a highly unsymmetrical structure with two unidentical * Correspondence author (e-mail: geeta.hundal@angelfire.com)…”

Heterocalixarenes Part 3: Bis-oxo-bridged calix[1]cyclicurea[3]arene and calix[1]cyclicurea[1]pyridine[2]arenes. Synthesis, X-ray crystal structure and conformational analysis 1

“…3). Imide carbonyl oxygen O( 1) is H-bonded to carbon C(15) of the methoxy group and aromatic carbon C( 11) of aryl unit B, whereas the oxygens of the bridging carbonyl groups, O(3) and O(4), are H-bonded to the bridging methylene carbons C (8) and C(31), respectively (Table 2).…”