Unique vapochromism of a paddlewheel-type dirhodium complex accompanied by dynamic structural and phase transitions

Kataoka, Yosuke; Kohara, Yoshihiro; Yano, Natsumi; Kawamoto, Tatsuya

doi:10.1039/d0dt02672g

Cited by 7 publications

(5 citation statements)

References 32 publications

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“…In fact, the 1 H NMR spectrum of ( S )- 1a Ph -TEG·DABCO in CDCl 3 was sharp, although some of the proton signals of ( S )- 1a Ph -TEG alone broadened (Figure S2a and b). This signal broadening of ( S )- 1a Ph -TEG is probably due to its dimerization or oligomerization driven by coordination of the carboxylate and peripheral amide carbonyl oxygen atoms or the ether oxygen atoms of the TEG chains to the axial coordination sites of the dirhodium(II) ions of another ( S )- 1a Ph -TEG, as reported in the literature . In DMSO, such oligomers dissociated into the free ( S )- 1a Ph -TEG, thus showing the sharp signals in the 1 H NMR spectrum in DMSO- d 6 as compared to those in CDCl 3 (Figure S2c).…”

Section: Results and Discussionsupporting

confidence: 67%

“…This signal broadening of (S)-1a Ph -TEG is probably due to its dimerization or oligomerization driven by coordination of the carboxylate and peripheral amide carbonyl oxygen atoms or the ether oxygen atoms of the TEG chains to the axial coordination sites of the dirhodium-(II) ions of another (S)-1a Ph -TEG, as reported in the literature. 120 In DMSO, such oligomers dissociated into the free (S)-1a Ph -TEG, 121 thus showing the sharp signals in the 1 H NMR spectrum in DMSO-d 6 as compared to those in CDCl 3 (Figure S2c). As already described, the poor polymerization ability of the 1:1 mixture of (S)-1a Ph -TEG and DABCO in CHCl 3 is ascribed to the weak second-coordination ability of DABCO to another open coordination site of dirhodium(II) in polar solvents.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Supramolecular Helical Assemblies of Dirhodium(II) Paddlewheels with 1,4-Diazabicyclo[2.2.2]octane: A Remarkable Substituent Effect on the Helical Sense Preference and Amplification of the Helical Handedness Excess of Metallo-Supramolecular Helical Polymers

et al. 2022

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We report unique coordination-driven supramolecular helical assemblies of a series of dirhodium(II) tetracarboxylate paddlewheels bearing chiral phenyl-or methyl-substituted amidebound m-terphenyl residues with triethylene glycol monomethyl ether (TEG) or n-dodecyl tails through a 1:1 complexation with 1,4-diazabicyclo[2.2.2]octane (DABCO). The chiral dirhodium complexes with DABCO in CHCl 3 /n-hexane (1:1) form onehanded helical coordination polymers with a controlled propeller chirality at the m-terphenyl groups, which are stabilized by intermolecular hydrogen-bonding networks between the adjacent amide groups at the periphery mainly via a cooperative nucleation−elongation mechanism as supported by circular dichroism (CD), vibrational CD, and variable-temperature (VT) absorption and CD analyses. The VT visible-absorption titrations revealed the temperature-dependent changes in the degree of polymerization. The columnar supramolecular helical structures were elucidated by X-ray diffraction and atomic force microscopy. The helix sense of the homopolymer carrying the bulky phenyl and n-dodecyl substituents is opposite those of other chiral homopolymers despite having the same absolute configuration at the pendants. A remarkably strong "sergeants and soldiers" (S&S) effect was observed in most of the chiral/achiral copolymers, while the copolymers of the bulky chiral phenyl-substituted dirhodium complexes with n-dodecyl chains displayed an "abnormal" S&S effect accompanied by an inversion of the helix sense, which could be switched to a "normal" S&S effect by changing the solvent composition. A nonracemic dirhodium complex of 20% enantiomeric excess bearing the less bulky chiral methyl substituents with n-dodecyl chains assembled with DABCO to form an almost onehanded helix (the "majority rule" (MR) effect), whereas the three other nonracemic copolymers showed a weak MR effect.

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Section: Results and Discussionsupporting

confidence: 67%

Section: ■ Results and Discussionmentioning

confidence: 99%

Supramolecular Helical Assemblies of Dirhodium(II) Paddlewheels with 1,4-Diazabicyclo[2.2.2]octane: A Remarkable Substituent Effect on the Helical Sense Preference and Amplification of the Helical Handedness Excess of Metallo-Supramolecular Helical Polymers

et al. 2022

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“…Fca-bearing paddlewheel-type Rh2 complexes are considered to be particularly interesting because this type of Rh2 complex shows excellent functional properties such as catalysis, sensing, and antitumor activities [29][30][31][32][33][34][35][36][37]. Homoleptic paddlewheel-type Rh2 complexes bridged with four fca derivative ligands, for example, [Rh2(fca)4], act as catalysts for carbene insertion, shape-selective alkane functionalization, and asymmetric intramolecular C-H insertion reactions [26,27,38]; however, the details of the synthesis, characterization, electrochemical and absorption properties, and X-ray crystal structures of the Rh2 complexes have not been previously reported.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, in this study, we closely investigated the synthesis, characterization, crystal structure, and absorption and electrochemical properties of fca-bearing homoleptic and heteroleptic paddlewheel-type Rh2 complexes, [Rh2(fca)4] (1; Scheme 1b) and [Rh2(fca)(piv)3] (2; piv = pivalate, Scheme 1c), using a combination of experimental and theoretical techniques. Fca-bearing paddlewheel-type Rh 2 complexes are considered to be particularly interesting because this type of Rh 2 complex shows excellent functional properties such as catalysis, sensing, and antitumor activities [29][30][31][32][33][34][35][36][37]. Homoleptic paddlewheel-type Rh 2 complexes bridged with four fca derivative ligands, for example, [Rh 2 (fca) 4 ], act as catalysts for carbene insertion, shape-selective alkane functionalization, and asymmetric intramolecular C-H insertion reactions [26,27,38]; however, the details of the synthesis, characterization, electrochemical and absorption properties, and X-ray crystal structures of the Rh 2 complexes have not been previously reported.…”

Section: Introductionmentioning

confidence: 99%

Ferrocene-Bearing Homoleptic and Heteroleptic Paddlewheel-Type Dirhodium Complexes

Kataoka,

Sato,

Yano

et al. 2024

Inorganics

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Two ferrocenecarboxylate (fca)-bridged dirhodium (Rh2) complexes, [Rh2(fca)4] (1) and [Rh2(fca)(piv)3] (2; piv = pivalate), were prepared through the carboxylate-exchange reactions of [Rh2(O2CCH3)4(H2O)2] and [Rh2(piv)4], respectively, with fcaH and characterized by 1H NMR, ESI-TOF-MS, and elemental analyses. Single-crystal X-ray diffraction analyses of [Rh2(fca)4(MeOH)2] (1(MeOH)2) and [Rh2(fca)(piv)3(MeOH)2] (2(MeOH)2), which are recrystallized from MeOH-containing solutions of 1 and 2, revealed that (1) 1(MeOH)2and 2(MeOH)2possess homoleptic and heteroleptic paddlewheel-type dinuclear structures, respectively; (2) both complexes have a single Rh–Rh bond (2.3771(3) Å for 1(MeOH)2, 2.3712(3) Å for 2(MeOH)2); and (3) the cyclopentadienyl rings of the fca ligands in 1(MeOH)2 adopt an eclipsed conformation, whereas those in 2(MeOH)2 are approximately 12–14° rotated from the staggered conformation. Density functional theory (DFT) calculations revealed that (1) the electronic configurations of the Rh2 core in 1(MeOH)2 and 2(MeOH)2are π4σ2δ2π*2δ*2π*2 and π4σ2δ2δ*2π*4, respectively; and (2) the occupied molecular orbitals (MOs) localized on the fca ligands are energetically degenerate and relatively more unstable than those on the Rh2 cores. Absorption features and electrochemical properties of 1 and 2 were investigated in a 9:1 CHCl3-MeOH solution and compared with those of fcaH and [Rh2(piv)4]. Through examining the obtained results in detail using time-dependent DFT (TDDFT) and unrestricted DFT, we found that 1 and 2 exhibit charge transfer excitations between the fca ligands and Rh2 cores, and 1 shows electronic interactions between ferrocene units through the Rh2 core in the electrochemical oxidation process.

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“…As is well known, this structural motif can be formed using most transition metal ions. Among them, dirhodium(II) (Rh 2 4+ ) complexes [1,[7][8][9][10], which have a single Rh-Rh bond originating from the σ 2 π 4 δ 2 δ* 2 π* 4 orbital interactions, are particularly interesting because of their excellent catalytic [11][12][13][14][15][16][17], sensing [18,19], and medical functionalities [20]. These functionalities are strongly influenced by the type of bridging ligand coordinated at the equatorial positions of the Rh 2 core.…”

Section: Introductionmentioning

confidence: 99%

6-Bromo-2-hydroxypyridinate-bridged Paddlewheel-Type Dirhodium Complex Isomers: Synthesis, Crystal Structures, Electrochemical Properties, and Structure-Dependent Absorption Properties

Sato,

Yano,

Kataoka

2024

Inorganics

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Two new paddlewheel-type dirhodium (Rh2) complex isomers, formulated as trans-2,2- and 3,1-forms of [Rh2(bhp)4] (bhp = 6-bromo-2-hydroxypyridinate), were obtained by the reaction of 6-bromo-2-hydroxypyridine with [Rh2(O2CCH3)4(H2O)2] and characterized by NMR, ESI-MS, and elemental analyses. Single crystal X-ray diffraction analyses clarified that the crystal structure of trans-2,2-form takes a conventional paddlewheel-type dimer structure with no axial coordination ligands, i.e., trans-2,2-[Rh2(bhp)4], whereas that of the 3,1-form changed significantly depending on the kinds of solvent used for crystallization processes; dimer-of-dimers-type tetrarhodium complex, i.e., 3,1-[Rh2(bhp)4]2, and a conventional paddlewheel-type dimer complex with an axial DMF ligand, i.e., 3,1-[Rh2(bhp)4(DMF)], were observed. The 3,1-form showed unique absorption changes that were not observed in the trans-2,2-form; the trans-2,2-form showed an absorption band at approximately 780 nm both in the solid state and in solution (CH2Cl2 and DMF), whereas the 3,1-form showed a similar absorption band at 783 nm in CH2Cl2 solution, but their corresponding bands were blue-shifted in solid state (655 nm) and in DMF solution (608 nm). The molecular structures and the origin of their unique absorption properties of these Rh2 complexes were investigated using density functional theory (DFT) and time-dependent DFT (TDDFT).

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Unique vapochromism of a paddlewheel-type dirhodium complex accompanied by dynamic structural and phase transitions

Abstract: The one-dimensional coordination polymer [Rh2(HA)4]n (1G; HA = hexanoate) exhibits a drastic vapochromic color change from green to red upon exposure to pyridine (py) vapor. Heating the red discrete complex...

Cited by 7 publications

References 32 publications

Supramolecular Helical Assemblies of Dirhodium(II) Paddlewheels with 1,4-Diazabicyclo[2.2.2]octane: A Remarkable Substituent Effect on the Helical Sense Preference and Amplification of the Helical Handedness Excess of Metallo-Supramolecular Helical Polymers

Supramolecular Helical Assemblies of Dirhodium(II) Paddlewheels with 1,4-Diazabicyclo[2.2.2]octane: A Remarkable Substituent Effect on the Helical Sense Preference and Amplification of the Helical Handedness Excess of Metallo-Supramolecular Helical Polymers

Ferrocene-Bearing Homoleptic and Heteroleptic Paddlewheel-Type Dirhodium Complexes

6-Bromo-2-hydroxypyridinate-bridged Paddlewheel-Type Dirhodium Complex Isomers: Synthesis, Crystal Structures, Electrochemical Properties, and Structure-Dependent Absorption Properties

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