Calix[2]thia[4]phyrin: an expanded calixphyrin with aggregation-induced enhanced emission and anion receptor properties.
The synthesis of calix[2]thia[4]phyrin 3, a core-modified expanded calixphyrin, by an efficient synthetic route is reported. 3 exhibits an aggregation-induced enhanced emission (AIEE) phenomenon upon addition of increasing amounts of water. This is attributed to the restricted intramolecular rotation of the meso-aryl rings present on the sp(3) bridging carbons. SEM studies revealed the formation of aggregation in an acetonitrile/water mixture with an average diameter of the aggregate in the range 0.38-2.08 μm. The photoluminescence quantum yield of 3 in 9:1 water/acetonitrile is 5-fold higher than the quantum yield in acetonitrile alone. Single-crystal X-ray analysis of 3 revealed a chairlike conformation stabilized by N-H···N and C-H···π intramolecular hydrogen-bonding interactions. Fluorine atoms on the meso-pentafluorophenyl groups are involved in C-H···F intermolecular hydrogen-bonding interactions to generate a two-dimensional supramolecular assembly in the solid state. In the diprotonated state, 3 has affinity for anions and forms 1:1 complexes with SO4(2-), NO3(-), Cl(-), and ClO4(-) in solution. The tetrahedral anions bind more strongly than the other anions. Single-crystal X-ray structure studies of the ClO4(-) anion complex with 3 revealed the formation of both 1:1 and 1:2 complexes in the solid state, with the host and the guest being held together by N-H···O hydrogen-bonding interactions.
School of Chemical Sciences, National Institute of Science Education and Research, IOP campus, Sainik School - PO, Bhubaneshwar 751005, Odisha, India.
Ganesan
G
Karthik
Pallavee Vitti
PV
Krushna
A
A
Srinivasan
Tavarekere K
TK
Chandrashekar
D000838:Anions / Q000737:chemistry; D018360:Crystallography, X-Ray; D047028:Macrocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*
D000838:Anions; D047028:Macrocyclic Compounds; D011166:Porphyrins; D013876:Thiophenes