Unravelling the Growth of Supramolecular Metal–Organic Frameworks Based on Metal-Nucleobase Entities

Abstract

The present work provides the basis to obtain three-dimensional (3D) extended porous supramolecular assemblies named supramolecular metal−organic frameworks (SMOFs). This goal can be achieved by considering three key factors: (i) the use of rigid building units, (ii) the establishment of predictable and rigid synthons between the building units, and (iii) the non-coplanarity of functional groups involved in the predictable synthons. Throughout this report we demonstrate the suitability of this synthetic strategy supported by six new SMOFs based on metal-nucleobase entities which fulfill the stated requirements: [Co(ThioG) 3 ] (SMOF-4; ThioG = thioguaninato), [Co(Hade) 2 X 2 ] (SMOF-5, SMOF-6; Hade = adenine and X = Cl − , Br − ), [Cu 8 (μ 3 -OH) 4 (μ 4 -OH) 4 (ade) 4 (μ-ade) 4 (μ-Hade) 2 ] (SMOF-7; ade = adeninato), [Cu 4 (μ 3 -ade) 4 (μade) 2 (pentylNH 2 ) 2 (CH 3 OH) 2 (CO 3 ) 2 (H 2 O) 2 ] (SMOF-8; pentylNH 2 = 1-pentylamine), and [Cu 2 (μ-ade) 2 (ade)(μ-OH)(H 2 O)(CH 3 OH)] n (SMOF-9). SMOF-4 is built up from monomeric entities in which bidentate thioguaninato ligands establish complementary hydrogen bonding interactions in non-coplanar directions leading to supramolecular layers that are further connected resulting in a porous structure with one-dimensional (1D) channels. The hydrogen bonding interactions among Watson−Crick and sugar edges of monomeric entities in SMOF-5 give rise to a triply interpenetrated supramolecular framework. Octameric clusters in SMOF-7 are self-assembled by hydrogen bonding to yield a porous 3D network. SMOF-8 is built up from tetranuclear units that are linked via base pairing interactions involving Watson−Crick faces to afford layers whose assembly generates a twodimensional pore system. SMOF-9 is in between pure MOFs and SMOFs since it consists of 1D infinite coordination polymers held together by complementary hydrogen bonding interactions into a 3D supramolecular porous structure.

Cu(II)–N6-Alkyladenine Complexes: Synthesis, X-ray Characterization and Magnetic Properties

“…All three complexes show two broad bands, one around 3400 cm −1 due to the presence of water and the other around 3300 cm −1 due to the presence of the exocyclic N-H group in adenine, as reported in the literature [23,24]. Typical bands of the N 1 -protonated adenine ring are observed at 1697-1698 cm −1 in the IR spectra of all three complexes, which are found approximately at a 30 cm −1 higher wave number than usual due to the coordination of adenine to the Cu atoms.…”

Enhancement of Intermolecular Magnetic Exchange through Halogen···Halogen Interactions in Bisadeninium Rhenium(IV) Salts

“…[1][2][3] Protonated and deprotonated nucleobases play a key role in many biochemical processes, and can also generate supramolecular compounds of interest in crystal engineering, molecular recognition, liquid crystals, molecule-based magnetism and materials science. [12][13][14][15][16][17][18][19] The nucleobase adenine presents up to four endocyclic (N1, N3, N7 and N9) and one exocyclic (N6) protonatable N-atoms (in basicity order: N9 > N1 > N7 > N3 > N6) which can afford a wide range of neutral tautomers and protonated forms (Chart 1). Both organic and inorganic salts based on mono-and diprotonated adenine [adeninium (B) or bisadeninium (C), respectively] are found in the literature.…”

Designs of 3-Dimensional Networks and MOFs Using Mono- and Polymetallic Copper(I) Secondary Building Units and Mono- and Polythioethers: Materials Based on the Cu–S Coordination Bond

“…Among the strong bonds one finds the classic M-OR and M-O 2 CR links, and a very large number of MOFs are also built upon M-N coordination bonds. Concurrently, the M-SR linkages where RS -is a thiolate have been employed in a somewhat less extent, but can clearly lead to MOFs and 3D coordination polymers, including copper as the metal (about 25 structures) [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Conversely, the weaker dative Cu(I):SRR' bond, where RSR' is either a cyclic or acyclic mono-or di-or polythioether have attracted less attention [28][29][30][31].…”