Isoreticular Two-Dimensional Covalent Organic Frameworks Synthesized by On-Surface Condensation of Diboronic Acids
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- 作者：J眉rgen F. Dienstmaier ; Dana D. Medina ; Mirjam Dogru ; Paul Knochel ; Thomas Bein ; Wolfgang M. Heckl ; Markus Lackinger
- 刊名：ACS Nano
- 出版年：2012
- 出版时间：August 28, 2012
- 年：2012
- 卷：6
- 期：8
- 页码：7234-7242
- 全文大小：599K
- 年卷期：v.6,no.8(August 28, 2012)
- ISSN：1936-086X
文摘
On-surface self-condensation of 1,4-benzenediboronic acid was previously shown to yield extended surface-supported, long-range-ordered two-dimensional covalent organic frameworks (2D COFs). The most important prerequisite for obtaining high structural quality is that the polycondensation (dehydration) reaction is carried out under slightly reversible reaction conditions, i.e., in the presence of water. Only then can the subtle balance between kinetic and thermodynamic control of the polycondensation be favorably influenced, and defects that are unavoidable during growth can be corrected. In the present study we extend the previously developed straightforward preparation protocol to a variety of para-diboronic acid building blocks with the aim to tune lattice parameters and pore sizes of 2D COFs. Scanning tunneling microscopy is employed for structural characterization of the covalent networks and of noncovalently self-assembled structures that form on the surface prior to the thermally activated polycondensation reaction.