Specimens of 14C-labeled poly(ethylene terephthalate), nylon 66, and poly(methyl methacrylate) have been synthesized and exposed, in vitro, to a number of enzyme solutions. Poly(ethylene terephthalate) was found to be affected by esterase and papain, although in different ways, but not by trypsin or chymotrypsin. Nylon 66 was unaffected by esterase but degraded by the other three. Poly(methyl methacrylate) was not affected by any of these enzymes. This indicates that some nominally stable polymers are susceptible to degradation by enzymes under some circumstances. The amount of degradation is small, but could have significant sequelae should it be reproduced in vivo.

Tetrasodium p-sulfonatocalix[4]arene exists as a hydrate with approximately 14 water molecules and has three polymorphic modifications, all of which contain a water molecule in the molecular cavity that is engaged in OH···π interactions. Single-crystal neutron structures are reported for two of these three forms and reveal a "compressed" water molecule with short OH bonds. Partial atomic charges and hardness analysis (PACHA) calculations based on the neutron coordinates give an OH···π interaction energy of 6.9-7.5 kJ mol(-1). The PACHA analysis also reveals the dominance of the charge-assisted hydrogen bonds from the Na(+)-coordinated water molecules. The instability of the crystal towards dehydration can be traced to an uncoordinated lattice water site. The remarkable calixarene-Na(+)-hydrate motif is conserved almost unchanged across all three polymorphs. A single-crystal neutron structure is also reported for pentasodium p-sulfonatocalix[4]arene·12H(2)O, which exhibits an intracavity water molecule that is engaged in both OH···π and OH···O hydrogen bonding. The shorter covalent bond to the hydrogen atom that forms the interaction with the aromatic ring is again apparent.

The reaction of 1,3,5-benzenetricarboxylic acid (H(3)BTC) with ZnSO(4).6H(2)O in a DMF-water solution afforded two new metal-organic frameworks [Zn(6)(mu(3)-OH)(2)(BTC)(4)(DMF)(2.5)(H(2)O)(2)].[Zn(H(2)O)(3)(DMF)(3)].3.1H(2)O (1) and Zn(2)(HBTC)(BTC)(H(2)O)(3)].DMA.3H(2)O (2). Both compounds are thermally stable and can be prepared reproducibly. Rehydration experiments on compound 2 demonstrate reversible dehydration and rehydration while 1 rehydrates to a different crystalline material. Network analysis revealed a binodal (3,6)-net for 1 and a (3,5)-net for 2, both rare topologies.

The reaction of 1,3,5-benzenetricarboxylic acid (H 3 BTRI) with ZnSO 4 •7H 2 O in DMF and H 2 O afforded [Zn 2 (μ 2 -OH 2 )(HBTRI)(BTRI)(H 2 O) 2 ]•DMA•3H 2 O (1). Compound 1 displays self-healing properties upon dehydration and rehydration as revealed by scanning electron microscopy. Further studies showed that 1 is flexible and able to absorb additional water molecules in high vapor pressure environments. The reaction of H 3 BTRI with Gd(NO 3 ) 3 •6H 2 O in DMF and H 2 O resulted in [Gd(BTRI)(H 2 O) 6 ] (2). It is also possible to form compound 2 through a solid-state process when crystals of 1 are placed into a solution of Gd(NO 3 ) 3 •6H 2 O in DMF and H 2 O. The reverse process does not occur.

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