Photoinduced Spin Transition for Iron(II) Compounds with Liquid-Crystal Properties

Hayami, Shinya; Motokawa, Natsuko; Shuto, Aya; Masuhara, Naoji; Someya, Takehiro; Ogawa, Yoshihiro; Inoue, Katsuya; Maeda, Yonezo

doi:10.1021/ic061646g

Cited by 49 publications

(22 citation statements)

References 24 publications

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“…The number of SCO metallomesogens is scarce, few examples of Fe(III) [9] , Co(II) [10] , and Fe(II) [11][12][13] have been reported so far. The first metallomesogen gathering SCO and LC properties corresponds to [Fe(LC)](PF 6 )] (LC ¼ Nalkyloxysalicylidenyl-N 0 -ethyl-N-ethylenediamine) (type iii)).…”

Section: Introductionmentioning

confidence: 99%

“…Mononuclear iron(II) and Co(II) metallomesogens in which the spin crossover and the smectic mesophases occur in different temperature intervals have been synthesized (type iii). [10,11] Later, Fe(II) metallomesogens where the spin crossover and liquid crystal transitions are synchronized in the same temperature region but not coupled have been reported. In the synthesized Fe(II) metallomesogens, [Fe(C n -trz) 3 ](4-MeC 6 H 4 SO 3 ) 2 Á xH 2 O, [12] spin state change occurs upon dehydration in the room temperature range where the materials show a discotic columnar mesophase D hd .…”

Section: Introductionmentioning

confidence: 99%

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Iron(II) Metallomesogens Exhibiting Coupled Spin State and Liquid Crystal Phase Transitions near Room Temperature

Seredyuk

Gaspar

Ksenofontov

et al. 2008

Adv Funct Materials

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Reaction of the ligand 2,2,2‐tris(2‐aza‐3‐((5‐akloxy)(6‐methyl)(2‐pyridyl))prop‐2‐enyl)ethane (Cn‐tameMe) with Fe(X)2 · sH2O salts afforded a series of spin crossover metallomesogens with general formula [Fe(Cn‐tame)](X)2 · sH2O (s ≥ 0), with n = 6, 10, 12, 14, 16, 17, 18, or 20 and X = ClO4− or BF4−. Single crystal X‐ray measurements have been performed on the [Fe(C6‐tameMe)](ClO4)2 (C6‐1) derivative at 100 K. The complex C6‐1 crystallizes in the triclinic system and adopts the Pbca space group. The iron(II) ion is in a distorted octahedral environment shaped by three imine and three pyridine nitrogen atoms of the Cn‐tameMe ligand. The average Fe–Nim and Fe–Npy bond distance is 1.918(2) Å and 2.084(2) Å, respectively, which are characteristic for the Fe(II) ion in the LS state. Neighbor molecules are packed in a head‐to‐head fashion forming a layered microsegregated structure. Ionic layer is composed of cationic spin crossover head‐groups and perchlorate anions, whereas alkyl tails are arranged into a non‐polar hydrocarbon layer. The complex [Fe(C18‐tameMe)](ClO4)2 (C18‐1) and the series [Fe(Cn‐tameMe)](BF4)2 (n = 10, 12, 14, 16, 17, 18, 20) (Cn‐2) series show thermally driven spin crossover and mesomorphism above 300 K. The thermotropic behavior of compounds Cn‐2 depends on the chain length defined by n. A common structural feature among all homologues of the series is a similar layered structure and adoption on melting of a smectic mesophase at ca. 350–375 K. Formation of the mesophase is due to the melting of the alkyl chains rather than a rearrangement of the ionic bilayers composed of polar SCO cations and BF4− or ClO4− anions. This gives rise to a mesophase with molten alkyl chains but with restricted movement through the ionic layer. Compounds Cn‐2 show thermochromic properties, they are dark violet in the LS state (T < 275 K, Cr) and become red in the HS state (T > 275 K, Cr, SX). These bi‐functional materials combine spin state change and mesomorphic behavior in a narrow interval of temperatures, 300–375 K.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Iron(II) Metallomesogens Exhibiting Coupled Spin State and Liquid Crystal Phase Transitions near Room Temperature

Seredyuk

Gaspar

Ksenofontov

et al. 2008

Adv Funct Materials

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“…In 2001, Galyametdinov and co-workers reported a compound of iron(III) which exhibits spin transition, followed by temperature dependent magnetic susceptibility and Mössbauer measurements, and smectic mesomorphism which was the first example of spin crossover in metallomesogens [28]. Later, different families of iron(II) and cobalt(II) systems were investigated and described [29][30][31][32][33][34][35].…”

Section: Spin Transition In Metallomesogens Of Iron(ii)mentioning

confidence: 99%

Mössbauer spectroscopy in molecular magnetism

et al. 2009

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The aim of this paper is to highlight some selected research activities on molecular magnetic materials using Mössbauer spectroscopy as a technique carried out in our laboratory in recent years. The first part of the present article is devoted to the studies of the various magnetic interactions, metal-to-metal electrontransfer phenomenon, glass transition occurring in molecular magnetic materials, whereas the second part deals with the iron(II) high spin (S = 2)-low spin (S = 0) transition phenomenon occurring in some isoxazole ligand based iron(II) compounds as examples with unusually complicated spin transition behaviour. Also, an example of a dinuclear a spin crossover compound of iron(II) is described, where Mössbauer spectroscopy has most convincingly unraveled the mechanism of the spin transition process. Finally, an example from our most recent studies of spin crossover materials exhibiting both thermal spin crossover and liquid crystalline properties in the same temperature interval near room temperature will be presented.

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“…In the past few years, a wide variety of metallomesogens has been synthesized based on salicylaldimine ligands [31][32][33][34][35][36][37][38][39][40][41]. First reports on mesogenic vanadyl complexes with salicylaldimine ligands were made by Galyametdinov et al [42].…”

Section: Introductionmentioning

confidence: 99%

Liquid-crystalline oxovanadium(IV) complexes accessed from bidentate [N, O] donor salicylaldimine Schiff-base ligands

Bhattacharjee

Das

Mondal

2011

Journal of Coordination Chemistry

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A series of bis[4-(n-alkoxy)-N-(4 0 -R-phenyl)salicylideneiminato]oxovanadium(IV) complexes (n ¼ 6, 10, 14, 16, 18 and R ¼ C 3 H 7 ) were prepared and their mesogenic properties were investigated. The mesomorphic behaviors of the compounds were studied by polarized optical microscopy and differential scanning calorimetry. Ligands display SmA/SmC and unexpected nematic mesophases. The complexes bearing longer alkoxy carbon chain (n ¼ 10, 14, 16, and 18) showed both monotropic or enantiotropic transitions with smectic A and high ordered smectic E phases. However, the complex with shorter carbon chain length (n ¼ 6) showed monotropic transition with an unprecedented nematic (N) phase. A density functional theory study was carried out using DMol3 at BLYP/DNP level to obtain a stable optimized structure. A squarepyramidal geometry for the vanadyl complexes has been suggested. A V¼O stretching value of $970 cm À1 corroborated absence of any V ¼ O Á Á Á V ¼ O interactions. Cyclic voltammetry revealed a quasireversible one-electron response at 0.61 V for the VO(IV)-VO(V) redox couple. Variable temperature magnetic susceptibility measurements of the vanadyl complexes suggested absence of any exchange interactions among the vanadyl spin centers.

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Photoinduced Spin Transition for Iron(II) Compounds with Liquid-Crystal Properties

Cited by 49 publications

References 24 publications

Iron(II) Metallomesogens Exhibiting Coupled Spin State and Liquid Crystal Phase Transitions near Room Temperature

Iron(II) Metallomesogens Exhibiting Coupled Spin State and Liquid Crystal Phase Transitions near Room Temperature

Mössbauer spectroscopy in molecular magnetism

Liquid-crystalline oxovanadium(IV) complexes accessed from bidentate [N, O] donor salicylaldimine Schiff-base ligands

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