2 O (3), where L [12][13][14][15][16] are N 3 -Schiff bases appended with linear C 12-16 carbon chains at the nitrogen atoms, were obtained in good yields by facile one-pot reactions. The single crystal X-ray structure of complex 1 shows a tetragonally compressed CoN 6 coordination geometry. The melting temperatures of 1 -3 were lower than 373 K, while their decomposition temperatures were above 473 K. All complexes have high-spin Co(II) centres at 300 K and exhibit a columnar mesophase above 383 K. Complexes 1 and 3 showed a normal thermal spin-crossover behaviour with weak hysteresis loops at about 320 K. Hence, these complexes showed uncoupled phase transitions (class iiia). 1 The values for the Seebeck coefficient (S e ) of the cobalt redox couples formed from 1 and 2 were 1.89±0.02 mV K -1 and 1.92±0.08 mV K -1 , respectively, identifying them as potential thermoelectrochemical materials.

The molecular optimisation strategies exhibit ultrahigh Seebeck coefficient through a six-pronged approach to maximise entropy during the transition from low spin (LS) to high spin (HS).

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