Tuning of ratiometric optical thermometry in the family of magnetic $\left\{{Nd_{1-x}}^{III}{{Yb^{III}}_{x}}[Cu_2^{I}\left ( CN \right )_5] \right\}$ frameworks showing the large SHG response

Three-dimensional (3D) coordination networks provide a stable framework preferable to designing materials with tunable properties by various chemical modifications, such as solvent exchange, element doping, etc. In this work, we explored extensively the 3D cyanido-bridged heterometallic assemblies having Nd(III) and Yb(III) centers in combination with polycyanidocuprate(I) ions, that is the family of $[Nd^{III}$$_{1-x}$$Yb^{III}$$_{x}(2,2′-bpdo)_{2}(H_{2}O)]$$[Cu^{I}$$_{2}(CN)5]·5H_{2}O$ (x = 0, 0.25, 0.5, 0.75, 1 (1–5); 2,2′-bpdo = 2,2′-bipyridine N,N′-dioxide) coordination networks. To form the lanthanide-incorporating molecule-based matrix, two different types of cuprate(I) moieties are spontaneously formed during crystallization, resulting in the trigonal planar tricyanido and tetrahedral tetracyanido copper(I)-based molecular anions. 1–5 reveal optical thermometry based on near-infrared (NIR) luminescence. The relative thermal sensitivity of the Nd(III)-containing 1 is considerably improved through the preparation of the analogous mixed heterometallic compounds by introducing Yb3+ ions, which enables also tunability over the operating temperature range. Since all 3D networks crystallize within a non-centrosymmetric Cc space group, they reveal a second harmonic generation (SHG) phenomenon, with the signal highest among the materials based on cyanido-bridged metal assemblies (the SHG efficiency of ~120% of the reference potassium dihydrogen phosphate). Furthermore, 1–5 show field-induced single-molecule magnet (SMM) behavior related to lanthanide(3+) ions, with the slow magnetic relaxation occurring via Raman and direct relaxation processes.