The recent breakthrough of attaining a blocking temperature near liquid N2 temperature rekindled the interest in lanthanide-based single molecule magnets (SMMs) for end-user applications.Within this realm,several chal...The recent breakthrough of attaining a blocking temperature near liquid N2 temperature rekindled the interest in lanthanide-based single molecule magnets (SMMs) for end-user applications.Within this realm,several challenges are present,with a key objective being the further enhancement of the blocking temperature.As the current set of molecules based on Dy^(III) have already reached their maximum potential barrier height for magnetisation reversal (Ueff),chemical insight-based developments are hampered.To address these challenges,using density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) methods,we have explored the possibility of obtaining lanthanide SMMs in high-valent oxidation states such as +4 and +5.We begin with various small models of [LnO_(2)]^(+),[LnO_(2)],and [LnO_(2)]- (Ln varying from Ce to Lu) systems to correlate the nature of the lanthanides to the SMM characteristics.We have also extended our study to include eight complexes reported earlier possessing +4 and +5 oxidation states to offer clues to improve the SMM characteristics.Our calculations reveal several advantages in fine-tuning the oxidation states in lanthanide SMMs,including the following: (i) increased lanthanide-ligand covalency compared to the Ln^(III) counterpart,(ii) a magnetisation reversal barrier height as high as 8424 cm-1,an unprecedented value compared to any models reported,(iii) among various ways to stabilise such high-oxidation states,encapsulation yielding several targets,with HoO_(2)@SWCNT(4,4) predicted to yield an impressive energy barrier of ∼5400 cm-1 and (iv) stronger lanthanide-ligand bonds that were also found to quench spin-phonon relaxation,as they offset the vibrations that cause this relaxation.These potentially yield higher blocking temperatures,offering a novel strategy for developing a new class of lanthanide SMMs.展开更多
基金A.S.is thankful to IITB for the IPDF.G.R.would like to thank SERB(SB/SJF/2019-20/12,CRG/2022/001697)for funding.
文摘The recent breakthrough of attaining a blocking temperature near liquid N2 temperature rekindled the interest in lanthanide-based single molecule magnets (SMMs) for end-user applications.Within this realm,several challenges are present,with a key objective being the further enhancement of the blocking temperature.As the current set of molecules based on Dy^(III) have already reached their maximum potential barrier height for magnetisation reversal (Ueff),chemical insight-based developments are hampered.To address these challenges,using density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) methods,we have explored the possibility of obtaining lanthanide SMMs in high-valent oxidation states such as +4 and +5.We begin with various small models of [LnO_(2)]^(+),[LnO_(2)],and [LnO_(2)]- (Ln varying from Ce to Lu) systems to correlate the nature of the lanthanides to the SMM characteristics.We have also extended our study to include eight complexes reported earlier possessing +4 and +5 oxidation states to offer clues to improve the SMM characteristics.Our calculations reveal several advantages in fine-tuning the oxidation states in lanthanide SMMs,including the following: (i) increased lanthanide-ligand covalency compared to the Ln^(III) counterpart,(ii) a magnetisation reversal barrier height as high as 8424 cm-1,an unprecedented value compared to any models reported,(iii) among various ways to stabilise such high-oxidation states,encapsulation yielding several targets,with HoO_(2)@SWCNT(4,4) predicted to yield an impressive energy barrier of ∼5400 cm-1 and (iv) stronger lanthanide-ligand bonds that were also found to quench spin-phonon relaxation,as they offset the vibrations that cause this relaxation.These potentially yield higher blocking temperatures,offering a novel strategy for developing a new class of lanthanide SMMs.
