In situ X-ray study of breathing-like effect in interlocked metal–organic nanocages

Using in situ-variable temperature single-crystal X-ray diffraction (VT-SCXRD) and solid-state quantum mechanical (QM) molecular modelling, the structural adaptability of mechanically interlocked M12L8 metal-organic cages (MOCs) including different guests is reported. Upon heating, the interlocked material shows a different response as a function of the guest's templating behavior, including a swelling and breathing-like effect of the M12L8 nanocages. The X-ray structures and solid-state QM calculations were used to analyse the energetic aspects related to the stability of the overall architectures. The energy of the 1D chains of interlocked M12L8 cages is investigated together with the stabilisation energy of M12L8 cages and M12L8 chains immersed in the crystalline phases. The role of the N-Zn-N coordination angles and the mechanical bonds in the breathing-like effect and the stability of the interlocked material is discussed.