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Retracted: Light‐Induced Bistability in Iron(III) Spin‐Transition Compounds of 5 X‐Salicylaldehyde Thiosemicarbazone (X=H, Cl, Br)
Author(s) -
Yemeli Eddy W. T.,
Blake Graeme R.,
Douvalis Alexios P.,
Bakas Thomas,
Alberda van Ekenstein Gert O. R.,
Koningsbruggen Petra J.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002100
Subject(s) - chemistry , crystallography , semicarbazone , spin transition , salicylaldehyde , spin crossover , photochemistry , stereochemistry , schiff base
The iron(III) spin‐crossover compounds [Fe(Hthsa)(thsa)] ⋅ H 2 O ( 1 ), [Fe(Hth5Clsa)(th5Clsa) 2 ] ⋅ H 2 O ( 2 ), and [Fe(Hth5Brsa)(th5Brsa) 2 ] ⋅ H 2 O ( 3 ) (H 2 thsa=salicylaldehyde thiosemicarbazone, H 2 th5Clsa=5‐chlorosalicylaldehyde thiosemicarbazone, and H 2 th5Brsa=5‐bromosalicylaldehyde thiosemicarbazone) have been synthesized and their spin‐transition properties investigated by magnetic susceptibility, Mössbauer spectroscopy, and differential scanning calorimetry measurements. The three compounds exhibit an abrupt spin transition with a thermal hysteresis effect. The more polarizable the substituent on the salicylaldehyde moiety, the more complete is the transition at room temperature with an increased degree of cooperativity. The molecular structures of 1 and 2 in the high‐spin state are revealed. The occurrence of the light‐induced excited‐spin‐state trapping phenomenon appears to be dependent on the substituent incorporated into the 5‐position of the salicylaldehyde subunit. Whereas the compounds with an electron‐withdrawing group (‐Br or ‐Cl) exhibit light‐induced trapped excited high‐spin states with great longevity of metastability, the halogen‐free compound does not, even though strong intermolecular interactions (such as hydrogen‐bonding networks and π stacking) operate in the system. For compound 2 , the surface level of photoconversion is less than 35 %. In contrast, compound 3 displays full photoexcitation.