Anion−π Interactions: Generality, Binding Strength, and Structure

Anion−π interactions have been systematically studied using tetraoxacalix[2]­arene[2]­triazine <b>1</b>, an electron-deficient and cavity self-tunable macrocyclic host, as an electron-neutral molecular probe. As revealed by electrospray ionization mass spectrometry (ESI-MS), fluorescence titration and X-ray crystallography, tetraoxacalix[2]­arene[2]­triazine has been found to form 1:1 complexes with four typical polyatomic anions of different geometries and shapes in the gaseous phase, in solution, and in the solid state. The association constants for the formation of anion−π complexes in acetonitrile are in the range of 239 to 16950 M^–1, following the order of <b>1</b>·NO₃^– > <b>1</b>·BF₄^– > <b>1</b>·PF₆^– > <b>1</b>·SCN^–. X-ray molecular structures of the complexes showed that two opposing triazine rings of tetraoxacalix[2]­arene[2]­triazine act as a pair of tweezers to interact with the included anions through cooperative anion−π and lone-pair electron−π interactions. The generality of anion−π interactions and diverse anion−π interaction motifs can provide a new dimension in the study of molecular recognition and self-assembly. Moreover, this study potentiates the effect of anion−π interactions in chemical and biological systems, especially those involving anion and electron-deficient aromatic species

Anion−π Interactions: Generality, Binding Strength, and Structure

Anion−π interactions have been systematically studied using tetraoxacalix[2]­arene[2]­triazine <b>1</b>, an electron-deficient and cavity self-tunable macrocyclic host, as an electron-neutral molecular probe. As revealed by electrospray ionization mass spectrometry (ESI-MS), fluorescence titration and X-ray crystallography, tetraoxacalix[2]­arene[2]­triazine has been found to form 1:1 complexes with four typical polyatomic anions of different geometries and shapes in the gaseous phase, in solution, and in the solid state. The association constants for the formation of anion−π complexes in acetonitrile are in the range of 239 to 16950 M^–1, following the order of <b>1</b>·NO₃^– > <b>1</b>·BF₄^– > <b>1</b>·PF₆^– > <b>1</b>·SCN^–. X-ray molecular structures of the complexes showed that two opposing triazine rings of tetraoxacalix[2]­arene[2]­triazine act as a pair of tweezers to interact with the included anions through cooperative anion−π and lone-pair electron−π interactions. The generality of anion−π interactions and diverse anion−π interaction motifs can provide a new dimension in the study of molecular recognition and self-assembly. Moreover, this study potentiates the effect of anion−π interactions in chemical and biological systems, especially those involving anion and electron-deficient aromatic species

Anion−π Interactions: Generality, Binding Strength, and Structure

Anion−π interactions have been systematically studied using tetraoxacalix[2]­arene[2]­triazine 1, an electron-deficient and cavity self-tunable macrocyclic host, as an electron-neutral molecular probe. As revealed by electrospray ionization mass spectrometry (ESI-MS), fluorescence titration and X-ray crystallography, tetraoxacalix[2]­arene[2]­triazine has been found to form 1:1 complexes with four typical polyatomic anions of different geometries and shapes in the gaseous phase, in solution, and in the solid state. The association constants for the formation of anion−π complexes in acetonitrile are in the range of 239 to 16950 M–1, following the order of 1·NO3– > 1·BF4– > 1·PF6– > 1·SCN–. X-ray molecular structures of the complexes showed that two opposing triazine rings of tetraoxacalix[2]­arene[2]­triazine act as a pair of tweezers to interact with the included anions through cooperative anion−π and lone-pair electron−π interactions. The generality of anion−π interactions and diverse anion−π interaction motifs can provide a new dimension in the study of molecular recognition and self-assembly. Moreover, this study potentiates the effect of anion−π interactions in chemical and biological systems, especially those involving anion and electron-deficient aromatic species

Anion−π Interactions: Generality, Binding Strength, and Structure

Anion−π interactions have been systematically studied using tetraoxacalix[2]­arene[2]­triazine <b>1</b>, an electron-deficient and cavity self-tunable macrocyclic host, as an electron-neutral molecular probe. As revealed by electrospray ionization mass spectrometry (ESI-MS), fluorescence titration and X-ray crystallography, tetraoxacalix[2]­arene[2]­triazine has been found to form 1:1 complexes with four typical polyatomic anions of different geometries and shapes in the gaseous phase, in solution, and in the solid state. The association constants for the formation of anion−π complexes in acetonitrile are in the range of 239 to 16950 M^–1, following the order of <b>1</b>·NO₃^– > <b>1</b>·BF₄^– > <b>1</b>·PF₆^– > <b>1</b>·SCN^–. X-ray molecular structures of the complexes showed that two opposing triazine rings of tetraoxacalix[2]­arene[2]­triazine act as a pair of tweezers to interact with the included anions through cooperative anion−π and lone-pair electron−π interactions. The generality of anion−π interactions and diverse anion−π interaction motifs can provide a new dimension in the study of molecular recognition and self-assembly. Moreover, this study potentiates the effect of anion−π interactions in chemical and biological systems, especially those involving anion and electron-deficient aromatic species

Anion−π Interactions: Generality, Binding Strength, and Structure

Anion−π interactions have been systematically studied using tetraoxacalix[2]­arene[2]­triazine <b>1</b>, an electron-deficient and cavity self-tunable macrocyclic host, as an electron-neutral molecular probe. As revealed by electrospray ionization mass spectrometry (ESI-MS), fluorescence titration and X-ray crystallography, tetraoxacalix[2]­arene[2]­triazine has been found to form 1:1 complexes with four typical polyatomic anions of different geometries and shapes in the gaseous phase, in solution, and in the solid state. The association constants for the formation of anion−π complexes in acetonitrile are in the range of 239 to 16950 M^–1, following the order of <b>1</b>·NO₃^– > <b>1</b>·BF₄^– > <b>1</b>·PF₆^– > <b>1</b>·SCN^–. X-ray molecular structures of the complexes showed that two opposing triazine rings of tetraoxacalix[2]­arene[2]­triazine act as a pair of tweezers to interact with the included anions through cooperative anion−π and lone-pair electron−π interactions. The generality of anion−π interactions and diverse anion−π interaction motifs can provide a new dimension in the study of molecular recognition and self-assembly. Moreover, this study potentiates the effect of anion−π interactions in chemical and biological systems, especially those involving anion and electron-deficient aromatic species

Data_Sheet_4_Hydroxy-Substituted Azacalix[4]Pyridines: Synthesis, Structure, and Construction of Functional Architectures.PDF

A number of hydroxyl-substituted azacalix[4]pyridines were synthesized using Pd-catalyzed macrocyclic “2+2” and “3+1” coupling methods and the protection–deprotection strategy of hydroxyl group. While the conformation of the these hydroxyl-substituted azacalix[4]pyridines is fluxional in solution, in the solid state, they adopted shape-persistent 1,3-alternate conformations. Besides, X-ray analysis revealed that the existence of hydroxy groups on the para-position of pyridine facilitated the formation of solvent-bridged intermolecular hydrogen bonding for mono-hydroxyl-substituted while partial tautomerization for four-hydroxyl-substituted macrocycles, respectively. Taking the hydroxyl-substituted azacalix[4]pyridines as molecular platforms, multi-macrocycle-containing architectures and functional building blocks were constructed. The self-assembly behavior of the resulting building blocks was investigated in crystalline state.</p

Data_Sheet_2_Hydroxy-Substituted Azacalix[4]Pyridines: Synthesis, Structure, and Construction of Functional Architectures.PDF

A number of hydroxyl-substituted azacalix[4]pyridines were synthesized using Pd-catalyzed macrocyclic “2+2” and “3+1” coupling methods and the protection–deprotection strategy of hydroxyl group. While the conformation of the these hydroxyl-substituted azacalix[4]pyridines is fluxional in solution, in the solid state, they adopted shape-persistent 1,3-alternate conformations. Besides, X-ray analysis revealed that the existence of hydroxy groups on the para-position of pyridine facilitated the formation of solvent-bridged intermolecular hydrogen bonding for mono-hydroxyl-substituted while partial tautomerization for four-hydroxyl-substituted macrocycles, respectively. Taking the hydroxyl-substituted azacalix[4]pyridines as molecular platforms, multi-macrocycle-containing architectures and functional building blocks were constructed. The self-assembly behavior of the resulting building blocks was investigated in crystalline state.</p

Synthesis, Structure, and Properties of Corona[6]arenes and Their Assembly with Anions in the Crystalline State

The synthesis, conformational structure, electronic property, and anion complexation of novel coronarenes were systematically studied. A number of corona[4]­arene[2]­tetrazines that contain different combinations of nitrogen atoms with O, S, SO₂, and CH₂ as bridging units were synthesized conveniently by means of a fragment coupling strategy based on efficient nucleophilic aromatic substitution reaction of easily available aromatic dinucleophiles and 3,6-dichlorotetrazine. The resulting macrocycles adopt crownlike conformational structures with the nitrogen bridge(s) forming conjugation with carbonyl and the other heteroatom linkages with tetrazine. CV and DPV measurements showed that the tetrazine-bearing coronarenes were electron deficient with reduction potentials ranging from −896 to −960 mV. Owing mainly to noncovalent anion−π attractive interactions, N₂,O₄-corona­[4]­arene­[2]­tetrazine formed complexes with anions of varied geometries and shapes yielding diverse assembled structures in the solid state

Data_Sheet_5_Hydroxy-Substituted Azacalix[4]Pyridines: Synthesis, Structure, and Construction of Functional Architectures.PDF

A number of hydroxyl-substituted azacalix[4]pyridines were synthesized using Pd-catalyzed macrocyclic “2+2” and “3+1” coupling methods and the protection–deprotection strategy of hydroxyl group. While the conformation of the these hydroxyl-substituted azacalix[4]pyridines is fluxional in solution, in the solid state, they adopted shape-persistent 1,3-alternate conformations. Besides, X-ray analysis revealed that the existence of hydroxy groups on the para-position of pyridine facilitated the formation of solvent-bridged intermolecular hydrogen bonding for mono-hydroxyl-substituted while partial tautomerization for four-hydroxyl-substituted macrocycles, respectively. Taking the hydroxyl-substituted azacalix[4]pyridines as molecular platforms, multi-macrocycle-containing architectures and functional building blocks were constructed. The self-assembly behavior of the resulting building blocks was investigated in crystalline state.</p

Data_Sheet_1_Hydroxy-Substituted Azacalix[4]Pyridines: Synthesis, Structure, and Construction of Functional Architectures.PDF

A number of hydroxyl-substituted azacalix[4]pyridines were synthesized using Pd-catalyzed macrocyclic “2+2” and “3+1” coupling methods and the protection–deprotection strategy of hydroxyl group. While the conformation of the these hydroxyl-substituted azacalix[4]pyridines is fluxional in solution, in the solid state, they adopted shape-persistent 1,3-alternate conformations. Besides, X-ray analysis revealed that the existence of hydroxy groups on the para-position of pyridine facilitated the formation of solvent-bridged intermolecular hydrogen bonding for mono-hydroxyl-substituted while partial tautomerization for four-hydroxyl-substituted macrocycles, respectively. Taking the hydroxyl-substituted azacalix[4]pyridines as molecular platforms, multi-macrocycle-containing architectures and functional building blocks were constructed. The self-assembly behavior of the resulting building blocks was investigated in crystalline state.</p