A New Bis(phthalocyaninato) Terbium Single-Ion Magnet with an Overall Excellent Magnetic Performance

Abstract

Bulky and strong electron-donating dibutylamino groups were incorporated onto the peripheral positions of one of the two phthalocyanine ligands in the bis(phthalocyaninato) terbium complex, resulting in the isolation of heteroleptic double-decker (Pc)Tb{Pc[N(CH)]} {Pc = phthalocyaninate; Pc[N(CH)] = 2,3,9,10,16,17,23,24-octakis(dibutylamino)phthalocyaninate} with the nature of an unsymmetrical molecular structure, a square-antiprismatic coordination geometry, an intensified coordination field strength, and the presence of organic radical-f interaction. As a total result of all these factors, this sandwich-type tetrapyrrole lanthanide single-ion magnet (SIM) exhibits an overall enhanced magnetic performance including a high blocking temperature (T) of 30 K and large effective spin-reversal energy barrier of U = 939 K, rendering it the best sandwich-type tetrapyrrole lanthanide SIM reported thus far.

Controlling the Crystal Field of Heteroleptic Bis(phthalocyaninato) Erbium for Field‐Induced Magnetic Relaxation

“…The heteroleptic bis(phthalocyaninato) crystal field composed of one electron‐donating substituted phthalocyanine has been reported to improve the SMM properties, including blocking temperature ( T B ) and energy barrier ( U eff ). [13a] However, the chemistry behind excellent heteroleptic bis(phthalocyaninato) lanthanide SIM about the structure‐magnetism relationship just was clarified by comparative researches with the help of crystal structures and theoretical calculations, as exemplified by a [(Pc)Tb{Pc{N(C 4 H 9 ) 2 } 8 }] · SIM. [13c] According to the theoretical calculations, the electrostatic potential around Tb ion for [(Pc)Tb{Pc{N(C 4 H 9 ) 2 } 8 }] · with one radical has been significantly increased in comparison with that of radical‐containing homoleptic [Tb(Pc) 2 ] · and [Tb{Pc{N(C 4 H 9 ) 2 } 8 } 2 ] · compounds, indicating the enhanced strength of crystal field for the heteroleptic species.…”

“…Furthermore, the relatively stable square‐antiprismatic (SAP) coordination geometry of sandwich‐type bis(tetrapyrrole) lanthanide compounds seems to be a necessary condition of SMMs for Tb/Dy species, which provides the availability in the fine adjustment of ligand field to handle the relationship between magnetic property and structure. As a result, the SMM investigation of sandwich‐type lanthanide double‐decker compounds was further spread to the whole family of multi(tetrapyrrole) lanthanide compounds including double‐deckers, triple‐deckers, quadruple‐deckers, quintuple‐deckers and even binuclear multiple‐deckers, revealing the effect of coordination geometry,[3a], [4b], [4c], [4d] intramolecular dipole‐dipole/coupling interaction,[2b], [5b], [6b] isotopes,[3c] electron‐donating groups[13a], [13c] on SMM functions. With the exception of intriguing sandwich‐type tetrapyrrole lanthanide SMMs, the interest in exploring much higher SMM performance is also continuously promoted by the development of other SMM systems with high energy barriers and blocking temperature .…”

Distribution of the unpaired electron in neutral bis(phthalocyaninato) yttrium double-deckers: An experimental and theoretical combinative investigation

“…However, at this temperature, both the heteroleptic double-deckers 2 and 4 show quite different spectra from their homoleptic analogs 1, 3 and 5, due to the observation of an asymmetrical rather than a symmetrical impulse signal in the range of 1000-2000 G, suggesting the unsymmetrical distribution of the radical over the two phthalocyanine rings in the heteroleptic double-decker molecules at low temperature. This, however, is not the case for the same compounds at room temperature [11]. Density functional theory (DFT) calculation results rationalize this conclusion.…”

“…All the bis(phthalocyaninato) yttrium complexes Y(Pc) 2 (1) (5) were prepared and isolated following the published procedures, which have been characterized by a series of spectroscopic methods in addition to elemental analysis [8][9][10][11].…”

Single‐Ion Magnet Investigation of ABAB‐Type Tetrachloro‐ and Tetraalkoxy‐Substituted Bis(phthalocyaninato) Terbium Double‐Decker with D2 Symmetrical Ligand Field

“…For the purpose of simplifying the calculations and qualitatively analyzing the symmetry change of crystal field in 1 , the electrostatic potential of anionic bis(ABAB‐phthalocyaninato) terbium compound 1 ′ composed of strong electron‐withdrawing chloride groups and electron‐donating methoxy groups on the peripheral and non‐peripheral positions, respectively, in comparison with that of unsubstituted bis(phthalocyaninato) terbium compound [(Pc)Tb(Pc)] – , was analyzed theoretically. It is worthy to note that the electrostatic potential is able to be used as an important parameter to evaluate the crystal field . Density functional theory (DFT) calculations on the basis of B3LYP/BSI were employed for molecular optimization and wave function analysis, using Gaussian 09 D.01 software package .…”