Single crystal of a one-dimensional metallo-covalent organic framework

Abstract

Although polymers have been studied for well over a century, there are few examples of covalently linked polymer crystals synthesised directly from solution. One-dimensional (1D) covalent polymers that are packed into a framework structure can be viewed as a 1D covalent organic framework (COF), but making a single crystal of this has been elusive. Herein, by combining labile metal coordination and dynamic covalent chemistry, we discover a strategy to synthesise single-crystal metallo-COFs under solvothermal conditions. The single-crystal structure is rigorously solved using single-crystal electron diffraction technique. The noncentrosymmetric metallo-COF allows second harmonic generation. Due to the presence of syntactic pendant amine groups along the polymer chains, the metallopolymer crystal can be further cross-linked into a crystalline woven network.

Divergent Chemistry Paths for 3D and 1D Metallo‐Covalent Organic Frameworks (COFs)

“…3D ED and PXRD techniques were applied to elucidate the structure of mCOF‐Cu (Figures c, d). The 3D ED data (Figure S23) reveals a monoclinic Bravais lattice with unit cell parameters of a =15.42 Å, b =29.15 Å, c =10.84 Å, and β =124.3° (possible space groups: C 2/ c or Cc , Table S2), which is in good agreement with that of mCOF‐Ag (a single‐crystalline 1D mCOF) . mCOF‐Cu and mCOF‐Ag were synthesized based on the same polydentate linkers and possess very similar FT‐IR spectra (Figure S21) and PXRD patterns (Figure S22).…”

“…mCOF‐Cu and mCOF‐Ag were synthesized based on the same polydentate linkers and possess very similar FT‐IR spectra (Figure S21) and PXRD patterns (Figure S22). Pawley fitting against the PXRD data (Figure c) shows that mCOF‐Cu has a refined unit of a =15.7397 Å, b =29.0446 Å, c =10.7550 Å, and β =123.15°, space group C2 (the symmetry was reduced into the subgroup C 2) . The agreement residuals are R wp =0.124, and R exp =0.076.…”

“…The 3D ED data ( Figure S23 Table S2), which is in good agreement with that of mCOF-Ag (a single-crystalline 1D mCOF). [13] mCOF-Cu and mCOF-Ag were synthesized based on the same polydentate linkers and possess very similar FT-IR spectra ( Figure S21) and PXRD patterns ( Figure S22). Pawley fitting against the PXRD data (Figure 3 c) shows that mCOF-Cu has a refined unit of a = 15.7397 , b = 29.0446 , c = 10.7550 , and b = 123.158, space group C2 (the symmetry was reduced into the subgroup C2).…”

“…When a homoleptic complex is added with a free polydentate linker to allow for ligand exchange, a dynamic combinatorial library, [12] whose constituents interconvert under dynamic equilibrium, is obtained (Figure 1 b). By performing the reactions under solvothermal conditions to facilitate dynamic covalent bond formation, a one-dimensional (1D) mCOF [13] (Figure 1 b) is obtained. The results presented in herein could be considered as a general principle for designing new mCOFs.…”

Three-dimensional electron diffraction for porous crystalline materials: structural determination and beyond

“…Atomic structures of several novel COF nanocrystals have been determined by 3DED. [98][99][100][101] The rst single crystal COF structure determined by 3DED was COF-320 ( Fig. 12a).…”