Dual Guest [(Chloride)3-DMSO] Encapsulated Cation-Sealed Neutral Trimeric Capsular Assembly: Meta-Substituent Directed Halide and Oxyanion Binding Discrepancy of Isomeric Neutral Disubstituted Bis-Urea Receptors
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- 作者：Utsab Manna ; Biswajit Nayak ; Gopal Das
- 刊名：Crystal Growth & Design
- 出版年：2016
- 出版时间：December 7, 2016
- 年：2016
- 卷：16
- 期：12
- 页码：7163-7174
- 全文大小：741K
- ISSN：1528-7505
文摘
A logically synthesized ortho-phenylenediamine based chloro-methyl disubstituted neutral organic bis-urea receptor L1 with the aid of three symmetry-independent units encapsulates an unusual triangular [(chloride)3-DMSO] guest assembly (complex 1a) via formation of DMSO + host + salt cocrystals within its trimeric paddle-wheel shaped cavity sealed by three n-TBA cations and exhibits diverse anion binding properties with oxyanions along with the chloride complex of its isomeric bromo-methyl disubstituted bis-urea receptor L2. Receptor L2 and L1 both form a similar kind of noncapsular 2:2 host–guest assembly in the presence of excess chloride (complex 2a) and acetate (complex 1b) respectively by noncooperative H-bonding interactions of urea groups which are attributed to the effect of meta-functionalization with respect to the adjacent N–H part of the urea moiety, whereas another planar oxyanion carbonate is doubly encapsulated within the tetrameric capsular cavity of L1 in the solid state (complex 1c). Moreover, receptor L2 conforms to a similar kind of cation sealed 2:1 host–guest pseudocapsular complex in the presence of larger coordinating anions such as tetrahedral sulfate (complex 2b) and octahedral hexafluorosilicate (complex 2c). 1H NMR titration experiments are also performed using n-TBA/TEA salts of anions to investigate the solution state anion binding behavior of isomeric L1 and L2 and corroborate the results obtained in the solid-state studies.