1,3,5-Triaza-7-phosphaadamantane-7-oxide (PTA=O): New Diamondoid Building Block for Design of Three-Dimensional Metal-Organic Frameworks

The facile self-assembly reactions of 1,3,5-triaza-7-phosphaadamantane-7-oxide (PTA=O) with AgNO3 or Ag2SO4 give rise to the generation of two new distinct silver organic frameworks [Ag(NO3)(mu(3)-PTA=O)](n) (1) and [Ag-2(mu(2)-SO4)(mu(s)-PTA=O)(H2O)](n) (2), respectively. They have been characterized by IR, H-1 and P-31{H-1} NMR spectroscopies, electrospray ionization-mass spectrometry (ESI-MS)(+/-), and elemental and single-crystal X-ray diffraction analyses, the latter featuring infinite three-dimensional (3D) non-interpenetrating networks driven by multiply bridging PTA=O spacers that adopt undocumented N2O- or N3O-coordination modes. The topological analysis of 1 reveals a uninodal 3-connected net with the point (Schlafli) symbol of (10(3)) and the srs topological type, whereas 2 shows a rare trinodal 3,4, 5-connected net with the unprecedented topology defined by the point symbol of (5.6.7)(5(4).6.8)(5(4).6(3).8(3)). Compounds 1 and 2 represent the first 3D metal-organic frameworks (MOFs) derived from PTA=O or any cage-like PTA derivative, thus opening up their underexplored applications as versatile building blocks in crystal engineering. Furthermore, 1 and 2 exhibit significant antibacterial and antifimgal activities studied in vitro against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans.