Cyclophanes possess a defined cavity size and are efficient in encapsulating and stabilising guest molecules inside the cavity through various non-covalent interactions. This unique property of the cyclophanes has been widely exploited for the development of selective probes for a variety of guest molecules. The present tutorial review highlights the use of various interesting functionalised cyclophane architectures for the sensitive and selective optical recognition of important biomolecules.

We synthesized a new class of picolylamine-porphyrin conjugates 1-3 and have investigated the effect of heavy atom insertion on their intersystem crossing efficiency through spin-orbit perturbations. By incorporating zinc ions in the core as well as periphery positions of the porphyrin ring, we have successfully optimized their triplet excited state quantum yields and their efficiency to generate singlet oxygen. Uniquely, the picolylamine-porphyrin conjugate 3 having five zinc ions exhibited a triplet excited state quantum yield of ca. 0.97 and a sensitized singlet oxygen generation yield of ca. 0.92. In contrast, the free base porphyrin derivative 1 exhibited ca. 0.64 and 0.5 of the triplet excited state and singlet oxygen quantum yields, respectively. Our results demonstrate that the insertion of zinc metal ions in the picolylamine-porphyrin conjugates not only quantitatively enhances the triplet excited state and singlet oxygen yields but also imparts hydrophilicity, thereby their potential use as sensitizers in photodynamic therapy and green photooxygenation reactions.

We demonstrate Cu(2+) ion induced formation of a novel water soluble metallocyclophane [.CuCl(2)](2), which uniquely recognizes guanosine 5'-monophosphate through changes in emission intensity utilizing synergistic effects of electrostatic, coordinative and pi-stacking interactions inside the cavity.

Magnetic phase control in two-dimensional CrOCl can be achieved through the application of strain and electric field. This leads to a ferromagnetic to antiferromagnetic phase transition and remarkable enhancement of the Curie temperature to 450 K.