Browsing by Author "Maeda, Matsuhiro"

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Alkoxy Chain Number Effect on Self-Assembly of a Trigonal Molecule at the Liquid/Solid Interface
(2019-11-07)
Tahara, Kazukuni
;
Nakayama, Ruri
;
Maeda, Matsuhiro
;
De Feyter, Steven
;
Tobe, Yoshito
We herein investigated the effect of the number of alkoxy chains on the two-dimensional self-assembly of a trigonal molecular building block. To this end, a dehydrobenzo[12]-annulene (DBA) derivative, DBA-OC14-OC1 having three tetradecyloxy chains and three methoxy groups in an alternating manner, was synthesized. Scanning tunneling microscopy (STM) observations at the 1,2,4-trichlorobenzene (TCB)/graphite interface revealed that DBA-OC14-OC1 forms three monolayer structures: porous honeycomb, parallelogram, and hexagonal A structures. At the 1-phenyloctane (PO)/graphite interface, DBA-OC14-OC1 also forms three structures: parallelogram, hexagonal B, and dense linear structures. In contrast to the previously reported DBA derivative DBA-OC14 having six tetradecyloxy chains, DBA-OC14-OC1 shows structural polymorphism with a variety of alkyl chain interaction modes. Because in the observed patterns DBA-OC14-OC1 adopts a low symmetric C-s or C-1 geometry, the variation of the interaction modes and the resulting network patterns likely originate from the conformational flexibility on surface of this DBA by decreasing the number of alkyl chains. Molecular mechanics simulations gave insight into the structural and energy aspects of this pattern formation. We also discussed the role of solvents, TCB and PO, on the polymorph formation.
Hierarchical two-dimensional molecular assembly through dynamic combination of conformational states at the liquid/solid interface
(2020-09-14)
Maeda, Matsuhiro
;
Nakayama, Ruri
;
De Feyter, Steven
;
Tobe, Yoshito
;
Tahara, Kazukuni
Self-sorting of multiple building blocks for correctly positioning molecules through orthogonal recognition is a promising strategy for construction of a hierarchical self-assembled molecular network (SAMN) on a surface. Herein we report that a trigonal molecule, dehydrobenzo[12]annulene (DBA) derivative having three tetradecyloxy chains and three hydroxy groups in an alternating manner, forms hierarchical triangular clusters of different sizes ranging from 2.4 to 16.4 nm, consisting of 3 to 78 molecules, respectively, at the liquid/graphite interface. The key is the dynamic combination of three different conformational states, which is solvent and concentration dependent. The present knowledge extends design strategies for production of sophisticated hierarchical SAMNs using a single component at the liquid/solid interface.