Coupling between the photo-excited cyclic π system and the 4f electronic system in a lanthanide single molecule magnet

Abstract

A new type of electronic interaction which couples two angular momenta, i.e. the angular momentum of a localized 4f system (J) and an orbital angular momentum generated in a cyclic π conjugated system by irradiation with a circularly-polarized light, has been identified in a lanthanide single molecule magnet.

Selective Stabilization of the Spin States of a Magnetically Anisotropic Dysprosium Ion Induced by Photo‐Excitation of the Associated Cyclic π‐Conjugated System

“…At 100 K, both the Q L and Q H bands show "normal" A-term patterns, in which DA varies from negative to positivew ith an increasing energy, meaningt hat the state excitedb yl cp light is higher in energy than that obtained by applying rcp light. This pattern is commonly seen in the isostructurald iamagnetic complexes [YPc 2 ] À and [LuPc 2 ] À [8,10] as well as in mono-Pc complexes, such as [ZnPc] and [MgPc]. [11] When aP cc omplex is in am agnetic field whose direction coincides the molecular four-fold symmetry axis (z axis), the doublyd egenerate p-p*e xcited states split into states with + j L z j and À j L z j .H ere, L z is the component of L along the molecular z axis.…”

“…Next, we describe the details of the employed method, of which we have given an outline in ap revious Communication for the [TbPc 2 ] À case. [8] Theoretical modeldescribing the MCD A-term for the coupled J-L system Our model consists of the followinga ssumptions and implementations. 1) The states to be considered are the doubly degenerate ground states J z ji ¼ AE ji and the four-fold-degenerate exciteds tates J z L z ji ¼ AEAE ji .2 )Both L and J are quantized along the four-fold molecular symmetry axis, denoted as the z…”

“…Because the measurements were performed in polymer matrices with a random orientation of molecules, the model must take into account the distribution of the angle between the direction of the magnetic field B and the molecular z axis. Next, we describe the details of the employed method, of which we have given an outline in a previous Communication for the [TbPc 2 ] − case …”

“…Recently, we reported the existence of a new type of electronic interactions that couples the 4 f‐electronic system with J and a photoexcited cyclic π‐conjugated system with an orbital angular momentum, that is, L in a double‐decker phthalocyanine‐terbium complex, that is, [TbPc 2 ] − (Pc 2− =phthalocyaninato) . Because such an interaction has never been recognized or studied in general for any lanthanide complexes, it is expected that there are unexplored properties and phenomena generated thereby.…”

Terbium(III) Phthalocyaninato Multiple-Decker Complexes in High Oxidation States: Correlation Between Electronic, Structural and Magnetic Properties and Unexpected Triplet Biradical States

“…For instance, Fukuda et al have reported that the monooxidized form of quadruple-decker complexes shows light absorption in the longer wavelength regions. 60 Light absorption in the wide range of wavelengths is helpful for light-harvesting materials in dye sensitized solar cells, for gathering the light from the sun as much as possible. In addition, nonlinear optical properties of multiple-decker complexes have been investigated by Jiang et al 22 From the point of view of molecular magnetism, various groups utilize the multiple-decker complexes having two Tb(III) and Dy(III) centers for analyzing the effect of intramolecular magnetic interactions which should affect the SMM properties.…”