Reversible SC‐SC Transformation involving [4+4] Cycloaddition of Anthracene: A Single‐Ion to Single‐Molecule Magnet and Yellow‐Green to Blue‐White Emission

Abstract

In search of magneto-optic materials, the mononuclear compounds Ln (depma)(NO ) (hmpa) (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single-ion to a single-molecule magnet with doubling of the spin reversal barrier energy and from yellow-green to blue-white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto-optic property.

Metal–Helix Frameworks Formed by μ3‐NO3− with Different Orientations and Connected to a Heterometallic CuII10DyIII2 Folded Cluster

“…The Dy 1 atom is nine‐coordinated in a spherical‐capped square antiprismatic geometry, which is completed by one terminal μ 2 ‐alkoxo O atom from one L 3− , one phenol O atom and one methoxy O from another L 3− , one μ 3 ‐MeO − group, one monodentate nitrate anion, and two chelating bidentate nitrate anions. The Dy−O bond lengths and O−Dy−O bond angles range within 2.243(8)–2.607(9) Å and 50.9(4)–157.7(4)°, respectively, which agree with those of previously reported Dy‐containing complexes . The Schiff base ligands are completely deprotonated with the phenol and two alkoxyl groups that coordinate in a trianionic form and present three different coordination modes in the complex: μ 3 ‐ η 1 : η 2 : η 1 : η 2 : η 1 , μ 6 ‐ η 1 : η 2 : η 1 : η 3 : η 2 , and μ 4 ‐ η 1 : η 2 : η 1 : η 2 : η 2 (Figure S1a, Supporting Information).…”

“…The DyÀOb ond lengths and OÀDyÀO bond angles range within 2.243(8)-2.607(9) and 50.9(4)-157.7(4)8,r espectively,w hich agree with those of previously reported Dy-containing complexes. [17] The Schiff base ligands are completely deprotonated with the phenol and two alkoxyl groups that coordinate in at rianionicf orm and present three differentc oordination modes in the complex: m 3 -h 1 :h 2 :h 1 :h 2 :h 1 , m 6 -h 1 :h 2 :h 1 :h 3 :h 2 ,a nd m 4 -h 1 :h 2 :h 1 :h 2 :h 2 ( Figure S1a, Supporting Information).…”

Thermo- and light-triggered reversible interconversion of dysprosium–anthracene complexes and their responsive optical, magnetic and dielectric properties

“…5, inset). The enthalpy is estimated to be À47.8 kJ mol À1 per molecule, which is comparable to those for Dy III 2 ðdepma 2 Þ(NO 3 ) 6 (hmpa) 4 (À46.8 kJ mol À1 for both de-dimerization and conformation change of depma 2 ), 40 and 3 -bis(salicylideneimino)diethylenetriamine] (À42.4 kJ mol À1 ). 55 Fig .…”

Alkyl Chain Length‐ and Polymorph‐Dependent Photomechanochromic Fluorescence of Anthracene Photodimerization in Molecular Crystals: Role of the Lattice Stiffness

“…Unlike MFC, whichi sw ell demonstrated in the literature, [10][11][12][13][14] examples of PMFC or PFC are very rare, [9,15] The [4+ +4] photodimerization of anthracenea nd its derivatives plays ac ritical role in our current understanding of topo-chemistry andi nt he development of photomechanical crystalline materials.T he topochemical principle of "minimum atomic and molecular movement" formulatedb yS chmidt and Cohen in the 1960s offers ag eneral guideline for predicting the feasibility ands tereochemistry of a [ 2 + +2] or [4+ +4] photodimerization reactioni nacrystallines olid. [16] Crystale ngineering under this guideline for effective photoreactions continues to be an attractive subject in materials chemistry [17][18][19] and supramolecular photochemistry. [20][21][22][23] On the other hand, examples [24,25] that deviate from the topochemical rules have prompted researcherst oa ddress the various aspects of crystalline media for photoreactions.…”