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Abstract: Two new ditopic porphyrin receptors Zn1 , incorporating a diaza-15-crown-5 unit, and Zn2 , incorporating a diaza-18-crown-6 unit, have been prepared and characterized. UV–vis study in polar methanol has revealed that Zn1 is able to selectively recognize sodium cyanide over potassium cyanide (the ratio of their binding constant is ca. 56), whereas Zn2 exhibits a higher binding affinity for potassium cyanide over sodium cyanide (the ratio of their binding constant is ca. 12). In contrast, both receptors display substantially weaker binding affinity for sodium thiocyanate and potassium thiocyanate presumably due to a monotopic binding fashion. [Copyright &y& Elsevier]

This paper describes studies on the synthesis, self-assembly behavior, and complexing properties of several strapped porphyrin-incorporated melamine–cyanuric or melamine-barbiturate-based rosette supramolecules in chloroform-d. Strapped porpyrin cyanuric acid H21 and its Zn (II) complex Zn1 were designed and synthesized. Both H21 and Zn1 could combine melamine derivatives 11 or 12 to afford porphyrin rosettes, which are more stable than the model rosette initially reported by Whitesides due to the larger size of the porphyrin unit. The new porphyrin rosettes could efficiently complex tripyridyl derivative 13 through intermolecular, cooperative coordination between Zn (II) and pyridine. Two new pyridine-bearing barbiturates 18a and 18b were also synthesized. Mixing the identical amount of 18a or 18b with 11 or 12 in chloroform-d led to the formation of new isomeric rosettes as a result of different orientation of the pyridine unit of 18a or 18b in the rosettes. 1H NMR study also revealed that porpyrin-bearing rosette Zn13·113 could complex pyridine-bearing rosette 113·18a3, leading to the formation of new two-layer-typed supramolecular architectures. [Copyright &y& Elsevier]

A novel strapped porphyrin receptor Zn1, in which two electron-rich bis(p-phenylene)-34-crown ether-10 units are incorporated, has been designed and synthesized from the newly developed intermediate 7 for investigating new chemistry of molecular recognition. 1H NMR and UV–Vis studies revealed that Zn1 displays relatively weak binding abilities to neutral electron deficient naphthalene-1,8,4,5-tetracarboxydiimide (NDI) derivatives 13 (no simple complexing stoichiometry was observed), 19 (Ka=48(±5) M−1) and 30 (Ka=46(±5) M−1) in chloroform-d, strong binding ability to pyridine derivative 25, (Ka=1.5(±0.12)×103 M−1) in chloroform, moderately strong binding ability to tetracationic compound 35·4PF6 (Ka=475(±50) M−1) in acetone-d6, and very strong binding affinity to compound 22 (Ka=6.5(±0.7)×105 M−1), which consists of one pyridine and two NDI units, in chloroform. Remarkable cooperative effect of the intermolecular metal–ligand coordination and donor–acceptor interactions in complex Zn1·22 was observed by comparing the complexing behaviors between Zn1 and the appropriately designed guests. Complex Zn1·22 possesses an unique three-dimensional tri-site binding feature. For comparison, the complexing affinity of 1 toward compounds 13, 19, and 30 in chloroform-d and 35·4PF6 in acetone-d6 has also been investigated and the binding patterns in different complexes were explored. The results demonstrate that strapped porphyrin derivatives are ideal precursors for constructing new generation of three-dimensional multi-site artificial receptors for molecular recognition and host–guest chemistry. [Copyright &y& Elsevier]

A novel and general approach has been developed to prepare l-tyrosine-containing porphyrins. The key intermediates, 2-tert-butoxycarbonylamino-3-(3-formyl-4-hexyloxy-phenyl)-propionic acid hexyl ester and 2-tert-butoxycarbonylamino-3-(3-formyl-4-methoxy-phenyl)-propionic acid methyl ester, were prepared by the Reimer–Tiemann reaction of Boc-protected l-tyrosine, which was followed by esterification and alkylation of the phenol hydroxide. A number of novel chiral l-tyrosine porphyrins were obtained from the reactions of 2-tert-butoxycarbonylamino-3-(3-formyl-4-alkoxy-phenyl)-propionic acid ester with different dipyrrolylmethanes and the reaction of 5-(4-trifluoromethylphenyl)pyrromethane afforded the highest yield. The tyrosine porphyrins could be readily deprotected to afford the corresponding diacid or diamine derivatives. [Copyright &y& Elsevier]

Abstract: The self-assembly of a novel series of donor–acceptor interaction-driven artificial hetero-duplexes in organic media has been described. Four linear compounds 1a–1d , bearing two to five electron rich 1,5-dioxynaphthalene units connected by the tetra(ethylene glycol) linker, respectively, have been prepared and used as donors, while eight compounds 2a–2d , 13–16 , bearing one to four electron deficient pyromellitic diimide, 1,4,5,8-naphthalene-tetracarboxydiimide, or perylene-3,4,9,10-tetracarboxydiimide units, respectively, have been used as acceptors. The structure of the hetero-duplexes has been characterized by the 1H NMR, UV–vis spectroscopy and vapor pressure osmometry. It is revealed that the binding stability of the duplexes vary greatly, depending on the length and structure of the monomers and also the solvent, and hetero-duplex 1d·2d displays a maximum association constant of ca. 1.0×104 M−1 in chloroform. [Copyright &y& Elsevier]

A hydrogen bonding approach has been developed to facilitate the self-assembly of a new series of rigid and planar metallocyclophanes. Two new anthranilamide derivatives 1 and 2, which are incorporated with two acetylene units, respectively, have been synthesized and characterized. X-ray analysis (for 1), 1D and 2D 1H NMR and IR experiments reveal that, due to the formation of intramolecular three-centered hydrogen bonding, both compounds adopt rigid and planar conformations with the two acetylene units located at the same side of the anthranilamide skeleton. Two new metallocyclophanes 17 and 18 have been constructed in moderate yields from the reaction of 1 and 2 with trans-Pt(PEt3)2Cl2, respectively, in dichloromethane in the presence of diethylamine and cupric chloride. Fluorescent and 1H NMR investigations reveal that both 17 and 18 can efficiently complex mono- and disaccharide derivatives in chloroform, with a binding selectivity for disaccharides, which is driven by intermolecular hydrogen bonding. [Copyright &y& Elsevier]

Abstract: Two linear compounds 1 and 2 have been designed and synthesized as new receptors for zinc porphyrins. Both compounds consist of two folded aromatic amide moieties, which are connected with an acetylene linker in 1 or directly in 2. The rigid conformations of their folded moieties are stabilized by intramolecular tri-centered hydrogen bonding, while the whole molecule adopts a ‘S’- or ‘C’-styled conformation depending on the relative orientation of the two rigid moieties. Two pyridine units are introduced at the ends of 1 and 2 for the complexation of zinc porphyrin guests. Although the 1H NMR investigation indicated that both compounds can bind two zinc porphyrin guests at high concentrations (≥5mM) in chloroform, the UV–vis studies revealed that, at low concentration of 1 and 2 (4μM), both compounds complex one zinc porphyrin guest to form structurally unique ‘two-point’-bound 1:1 complexes. The association constants of the 1:1 complexes have been determined with the UV–vis titration experiments. [Copyright &y& Elsevier]