Although not covered in this review (given the focus on structural and magnetic properties), it is worth noting that Ln-based calixarene complexes have fascinating luminescent properties which can be tuned / manipulated through synthetic alteration of the C[n] framework. A relatively recent review by Massi and Ogden highlights the antenna effect calixarenes can provide in such complexes, but also covers early work in which the photophysical properties of compound 30 in detail. The Ln-based systems covered herein should be revisited to study such properties in detail, and indeed any further examples isolated should be studied to provide greater insight into how these species may be incorporated into materials, for example.