Visual determination of aliphatic diamines based on host–guest recognition of calix[4]arene derivatives capped gold nanoparticles

• A facile and versatile method for one-pot synthesis of macrocycle functionalized AuNPs is proposed.
• With as-prepared calix[4]arene crown ether (CCE4) functionalized AuNPs, visual host–guest recognition of diamines is carried out successfully.
• The sensing of diamines is mediated by the size-selective encapsulation of amine guest into the cavity of the macrocycle host.
• This very simple method might also be expanded to other macrocycles for the functionalization of nanomaterials.

Since amine compounds have been widespread pollutants in nature and they are extensively used in pharmaceutical industeries and dye manufacturing, it is highly desirable to develop simple, effective and naked-eye available analytical methods for such aliphatic diamines determination. Calixarenes as macrocycles have drawn intensive interests for fields such as biomedicine, supramolecular chemistry and smart materials. Here, instead of the normal complicated modification strategy, a facile and efficient method for one-pot synthesis of calix[4]arene crown ether (CCE4) capped gold nanoparticles (AuNPs) is proposed. The as-prepared CCE4–AuNPs are not only high water dispersity and stability even after storage for 3 months, but also capable of host–guest recognition of diamines in aqueous systems. Size-selective encapsulation of amine group between CCE4 and diamines carry out the aggregation of CCE4–AuNPs. The determination of diamines such as hexamethylenediamine or spermine can be realized by the UV–vis absorbance change and visual color difference.