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Control of optically active structure of thioether‐phthalocyanine aggregates by chiral Pd(II)‐BINAP complexes in toluene and at the toluene/water interface
Author(s) -
Adachi Kenta,
Chayama Kenji,
Watarai Hitoshi
Publication year - 2006
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20293
Subject(s) - chemistry , binap , toluene , chirality (physics) , thioether , photochemistry , crystallography , stereochemistry , organic chemistry , enantioselective synthesis , catalysis , chiral symmetry breaking , physics , quantum mechanics , quark , nambu–jona lasinio model
The Pd(II)‐2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP)‐mediated chiral assembly of thioether‐derivatised phthalocyanatomagnesium(II) compounds (MgPc(SR) 8 , SR is benzylthio (SBz) or benzhydrylthio (Bh)) was formed in toluene and at the toluene/water interface, and investigated by means of UV‐Vis absorption and circular dichroism (CD) spectroscopy combined with the centrifugal liquid‐membrane (CLM) devise. Interfacial tension measurements indicated that, in the presence of PdSO 4 in the aqueous phase, BINAP ligand adsorbed as a monolayer forming Pd(II)BINAP 2+ complex at the toluene/water interface. UV‐Vis absorption spectrum of MgPc(SR) 8 in the Q‐band region was blue‐shifted in toluene upon addition of [Pd(II)BINAP]Cl 2 , but red‐shifted at the toluene/water interface when Pd(II)BINAP 2+ was formed at the interface. These results suggested that MgPc(SR) 8 ‐Pd(II)BINAP complex formed H ‐aggregate (face‐to‐face type) in toluene solution and J ‐aggregate (end‐to‐end type) at the toluene/water interface, respectively. Moreover, the specific bisignate CD spectral pattern in both systems indicated that the aggregates of MgPc(SR) 8 ‐Pd(II)BINAP complexes were chirally twisted, well controlled by the chirality of BINAP ligand. Very interestingly, the morphology of MgPc(SBz) 8 ‐Pd(II)BINAP and MgPc(SBh) 8 ‐Pd(II)BINAP aggregates formed at the toluene/water interface were significantly different as the rodlike and the ribbonlike crystalline structure, respectively, as observed by a scanning electron microscopy (SEM). On the basis of these experimental results, we proposed schematic molecular models of the chiral aggregates of MgPc(SR) 8 ‐Pd(II)BINAP complexes and demonstrated the specific role of the toluene/water interface. Chirality, 2006. © 2006 Wiley‐Liss, Inc.