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Cavitand‐Based Pd‐Pyridyl Coordination Capsules: Guest‐Induced Homo‐ or Heterocapsule Selection and Applications of Homocapsules to the Protection of a Photosensitive Guest and Chiral Capsule Formation
Author(s) -
Nakamura Munechika,
Tsukamoto Yoshimi,
Ueta Takuro,
Sei Yoshihisa,
Fukushima Takanori,
Yoza Kenji,
Kobayashi Kenji
Publication year - 2020
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.202000603
Subject(s) - cavitand , chemistry , supramolecular chemistry , stereochemistry , moiety , chirality (physics) , capsule , crystallography , crystal structure , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark , botany , biology
A 2 : 4 mixture of tetrakis[4‐(4‐pyridyl)phenyl]cavitand ( 1 ) or tetrakis[4‐(4‐pyridyl)phenylethynyl]cavitand ( 2 ) and Pd(dppp)(OTf) 2 self‐assembles into a homocapsule { 1 2  ⋅ [Pd(dppp)] 4 } 8+  ⋅ (TfO − ) 8 ( C1 ) or { 2 2  ⋅ [Pd(dppp)] 4 } 8+  ⋅ (TfO − ) 8 ( C2 ), respectively, through Pd−Npy coordination bonds. A 1 : 1 : 4 mixture of 1 , 2 , and Pd(dppp)(OTf) 2 produced a mixture of homocapsules C1 , C2 , and a heterocapsule { 1  ⋅  2  ⋅ [Pd(dppp)] 4 } 8+  ⋅ (TfO − ) 8 ( C3 ) in a 1 : 1 : 0.98 mole ratio. Selective formation (self‐sorting) of homocapsules C1 and C2 or heterocapsule C3 was controlled by guest‐induced encapsulation under thermodynamic control. Applications of Pd−Npy coordination capsules with the use of 1 were demonstrated. Capsule C1 serves as a guard nanocontainer for trans ‐4,4′‐diacetoxyazobenzene to protect against the trans ‐to‐ cis photoisomerization by encapsulation. A chiral capsule { 1 2  ⋅ [Pd(( R )‐BINAP)] 4 } 8+  ⋅ (TfO − ) 8 ( C5 ) was also constructed. Capsule C5 induces supramolecular chirality with respect to prochiral 2,2′‐bis(alkoxycarbonyl)‐4,4′‐bis(1‐propynyl)biphenyls by diastereomeric encapsulation through the asymmetric suppression of rotation around the axis of the prochiral biphenyl moiety.

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