Solvatomorphs of 25,26,27,28- tetrahydroxycalix[4]arene and 5,11,17,23-tetramino-25,26,27,28-tetrabutoxycalix[4]arene: quenching photoluminescence through switching the guest

DA SILVA NETO, L.; DE FÁTIMA, A.*; MARTINS, F. T.*; MOREIRA DA SILVA, C.; QUEIROZ MAIA, L. J.; SAROTTI, A.M.

CRYSTENGCOMM

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2017 vol. 19 p. 1792 - 1800

1466-8033

Here we have disclosed two solid state forms of 5,11,17,23-tetramino-25,26,27,28-tetrabutoxycalix[4]arene (1) and two onesof the non-functionalized 25,26,27,28- tetrahydroxycalix[4]arene(2). This is the first structural knowledge of a tetra-aminofunctionalized calixarene derivative, even though this compoundis well known and used as precursor of several otherfunctionalized calix[4]arenes. The two solid forms of 1 differ bypresence of either water or water/dimethylsulfoxide (DMSO)solvent molecules entrapped into the major calixarene cavity,even though pinched conformation is adopted in both forms as aconsequence of contacts between solvent molecules and phenylrings. Likewise, the switch of water for DMSO into cone cavity of 1has abrogated photoluminescence (PL) found only in the dihydrateform. Frontier molecular orbitals calculations at the B3LYP/6-31G*level of theory support a short-range electron transfer betweenguest (DMSO) and host (1) molecules quenching the solid statephotoluminescence whether DMSO is entrapped into the cone.This solvatomorphism approach for PL search in calixarenes opensperspective of tuning and even increasing this performance ofcalixarenes through changing the guest solvent molecule.Similarly, the two crystal forms of 2 entrap either methyl alcoholor DMSO into its cone, which, as well as both crystal forms of 1,have packed into sheets through different fashions and contactspattern