Molecular Assemblies of Metal Complexes via Base‐Pairing of Nucleic Acids in the Crystalline State

Abstract

The nature of the molecular assemblies formed in the crystalline state by cobalt(II) terpyridine (terpy) complexes incorporating appended adenine (A) or thymine (T) bases was found to be controlled by which bases are present. Single-crystals of the cobalt(II) complexes [Co(A-C6-terpy) ](BF ) (1) and [Co(T-C6-terpy) ](BF ) (2) have needle and block habits, respectively. Subsequent mixing of 1 and 2 in MeOH resulted in isolation of [Co(A-C6-terpy) (T-C6-terpy) ](BF ) (3) as plate-like crystals. A 3D network structure is present in 1 that incorporates 1D chains, whereas 2 adopts a 2D stacked structure constructed from ladder-type assemblies. For 3, "dimer-rings" consisting of [Co(A-C6-terpy) ] and [Co(A-C6-terpy)(T-C6-terpy)] units are generated by means of base-pairing between A and T. Notably, 3 displays the first crystal structure of a heteroleptic cobalt(II) complex of [Co(A-C6-terpy)(T-C6-terpy)](BF ) . These assembly differences involving the terpyridine cobalt(II) complex units in 1-3 affect the cooperativities influencing their spin crossover (SCO) behavior. The influence of the terminal nucleobases on the resulting assembly has been probed by investigating the co-crystallization of [Co(terpy) ](BF ) (4) with [Co(C6-terpy) ](BF ) (5) and 1 with 5.

Slow Magnetic Relaxation Triggered by a Structural Phase Transition in Long-Chain-Alkylated Cobalt(II) Single-Ion Magnets

“…The Co–N distances are Co–N(1) = 2.153 Å, Co–N(2) = 2.025 Å, and Co–N(3) = 2.142 Å, respectively. The bond lengths are consistent with those of typical HS Co­(II) compounds. − The selected bond lengths and angles for 1 ·2MeOH are summarized in Table S2. In order to discuss the structural distortions of the [CoN6] core, the distortion parameters Σ and φ were calculated, where Σ is the sum of |90 – α| for the 12 angles of cis -N–Co–N and φ is the interligand angles for trans -N–Co–N. , A perfectly octahedral structure gives Σ = 0 and φ = 180.…”

“…Spin transition (ST) phenomena in bis-terpyridine Co­(II) derivatives have been widely investigated, in part due to their ease of modification. − However, most of these complexes are in their low-spin (LS) state or exhibit spin crossover (SCO) behavior arising from strong ligand fields and high-symmetry structures; as a consequence, it is normally difficult to generate their corresponding high-spin (HS) states. Nevertheless, the generation of a HS species induced via intermolecular interactions between bound modified terpyridine ligands is expected to show enhanced magnetic anisotropy because of the resulting distorted coordination environment of the Co­(II) ion.…”

Ab initio calculation of magnetic anisotropy and thermal spin transition in the variable temperature crystal conformations of [Co(terpy)2]2+

“…À , NCS À , NO 3 À , [Co(CN) 4 ] 2À , SO 4 2À , BPh 4 À and n = 0-6) exhibit different SCO behaviour, resulting in incomplete or gradual SCO curves. 20,22,24,25,[27][28][29][30][31] Kilner and Halcrow have reported a crystallographic study of [Co(terpy) 2 ][BF 4 ] 2 at nine temperatures between 30-375 K. The complex shows a gradual thermal spintransition with SCO temperature near 270 K. 32 Long alkyl chains in SCO cobalt(II) complexes can result in new physical properties due to the interaction between SCO and response to external stimuli, as well as the coordination of spin-state transitions and crystal-liquidcrystal phase transitions. 10,28 A range of Co(II) complexes have been studied for their spin-crossover behavior, with some showing very high transition temperatures.…”

Engineering of the XY Magnetic Layered System with Adeninium Cations: Monocrystalline Angle-Resolved Studies of Nonlinear Magnetic Susceptibility

“…In this work, we make a step toward crystal engineering of coordination layered magnets using topologically advanced components. This inspiration came from the field of biochemistry: the purine- and pyrimidine-type nucleic bases offer the unique side double or triple hydrogen bond patterns owing to the specific distribution of N-heteroatoms and N–H, CO, and NH 2 functions. − Considering the above, and driven also by simple curiosity, we carried out self-assembly tests toward the formation of new solid phases involving {Cu II [M V (CN) 8 ]} − , using acidic aqueous solutions as a medium. As a result, we present the crystal structure and complete angle-resolved magnetic studies of (AdeH)­{Cu II [W V (CN) 8 ]}·2H 2 O ( 1 ) (AdeH + , adeninium cations).…”