Synthesis of novel Lower-rim minoxidil substituted calix[4]arene: New sensitive and selective fluorescent sensor for Cu2+

Supramolecular chemistry deals with reversible noncovalent interactions such as electrostatics, hydrogen binding, van der Waals and donor–acceptor interactions between two or more molecules or ions.1 Macrocyclic hosts such as crown ethers, cryptands, cyclophanes, calixarenes and cucurbiturils have been synthesized and received much attention, opening a wide range of opportunities for new supramolecular chemistry.2 Calixarenes are examples of metacyclophanes which are composed of phenol and methylene bridge units.3 These cyclic oligomers are useful for the building-up of the functionalized host molecules. Minoxidil, a piperidinopyrimidine, was initially developed as an antihypertensive agent by The Upjohn company.4 This molecule has an oxygen and five nitrogen atoms in an arraye which can make minoxidil such a suitable ligand to interact with various ions, in particular metal cations. Thus, we have used minoxidil to introduce two active site at the lower rim of calix[4]arene annulus which can selectively recognize Cu2+. The synthesize of the target molecule has been summarized below. The structure of the product was determined by HRMS, 1H and 13C NMR and IR spectroscopic data.

Keywords:

Supramolecular chemistry , Noncovalent interactions , Host-guest chemistry , Chemosensors , Calix[4]arenes , Minoxidil