AUTHOR=Ghosh Mithun Kumar , Jana Barun , Ghorai Tanmay Kumar 

TITLE=Single Molecule Magnets of Co2 and Co2La MOFs Synthesized by New Schiff Base Ligand N,N′-bis(o-Vanillinidene) Ethylenediamine (o-VEDH2)

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.571223

DOI=10.3389/fchem.2020.571223

ISSN=2296-2646

ABSTRACT=<p>Schiff base ligand N,N′-bis(<italic>o</italic>-vanillinidene) ethylenediamine (<italic>o</italic>-VEDH<sub>2</sub>) has been employed to synthesize new [Co<sup>II</sup>Co<sup>IV</sup>(<italic>o</italic>-VED)(OAc)<sub>2</sub>(μ<sub>2</sub>-OAc)(OMe)]•MeOH (<bold>1</bold>) and [<inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>Co</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mtext>IV</mml:mtext></mml:mrow></mml:msubsup></mml:math></inline-formula>(<italic>o</italic>-VED)<sub>2</sub>(en)<sub>2</sub>(NCCH<sub>3</sub>)(OCH<sub>3</sub>)][La(NO<sub>3</sub>)<sub>6</sub>](<inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>NO</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:mo>−</mml:mo></mml:mrow></mml:math></inline-formula>)•2MeOH•MeCN•H<sub>2</sub>O (<bold>2</bold>) metal–organic frameworks (MOFs) that have interesting single molecule magnets (SMMs) property. The synthesized complexes are characterized by single crystal X-ray diffraction, fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, and squid magnetic measurement. Single crystal X-ray data show that both complexes crystallize in the monoclinic crystal system with <italic>P</italic>2<sub>1</sub>/<italic>c</italic>(14) and <italic>P</italic>2<sub>1</sub>/<italic>n</italic>(14) space groups and generate unique MOF-like structures. Overall, both the metal centers of <bold>1</bold> form octahedral geometry with a butterfly core structure. Variable temperature (<italic>T</italic>) and field (<italic>H</italic>) solid-state direct-current (dc) and alternative current (ac) magnetic susceptibility measurements were performed on both the complexes over 1.8 to 300 K, which exhibited a ground state spins (S) of 4 and 5 of complexes <bold>1</bold> and <bold>2</bold>, respectively. The AC out-phase and in-phase properties of complexes show SMMs. Other properties such as optical, sensing, and DNA-binding interactions were also investigated by the complexes. Complexes <bold>1</bold> and <bold>2</bold> have energy band gaps of 3.7 and 3.03 eV indicating semiconductor properties. Simultaneously, complex <bold>1</bold> was found to sense H<sub>2</sub>O<sub>2</sub> with a rate constant (<italic>k</italic>) = 1.59 × 10<sup>−4</sup> s<sup>−1</sup>, whereas complex <bold>2</bold> was found to bind with calf-thymus–DNA by intercalation mode with binding constant (<italic>K</italic><sub><italic>b</italic></sub>) of 1.22 × 10<sup>5</sup> M<sup>−1</sup>.</p>