Water's Role in Polymorphic Platinum(II) Complexes.

Solvent plays a vital role in the recrystallization process and resulting crystallinity of materials. This role is of such importance that it can control the stability and utility of materials. In this work, the inclusion of a solvent in the crystalline lattice, specifically water, drastically affects the overall stability of two platinum polymorphs. [Pt(tpy)Cl]BF4 (tpy = 2,2';6'2″-terpyridine) crystallizes in three forms, red (1R) and blue (1B) polymorphs and a yellow nonsolvated form (2). 1R is the more stable of the two polymorphs, whereas 1B loses crystallinity upon dehydration at ambient conditions resulting in the formation of 2. Close examination of the solid-state extended structures of the two polymorphs reveals that 1R has a lattice arrangement that is more conducive to stronger intermolecular interactions compared to 1B, thereby promoting greater stability. In addition, these two polymorphs exhibit unique vapochromic responses when exposed to various solvents.

Spectroscopic Characterization of Platinum(IV) Terpyridyl Complexes.

Pt(tpy)X3+ [X = Cl (1), Br (2); tpy = 2,2':6',2″-terpyridine] salts were prepared by the oxidative addition of Pt(tpy)X+ with X2 as originally reported by Morgan and Burstall in 1934. The complexes have been fully characterized by 1H NMR spectroscopy, elemental analysis, mass spectrometry, and X-ray crystallography. The electronic structures of 1 and 2 were investigated using absorption and emission spectroscopy, and the accumulated data are consistent with stabilization of the singlet ligand-centered and potentially singlet ligand field/singlet ligand-to-metal charge-transfer states for 1 and 2 compared to those for Pt(tpy)Cl+ (3) and Pt(tpy)Br+ (4). The changes in the lowest-energy-absorbing state result in drastic differences in the emission behavior among 1-4. Specifically, 1 emits from a lowest-energy state that appears to have triplet ligand field/triplet ligand-to-metal charge-transfer character, whereas 2 exhibits no appreciable emission between 400 and 800 nm.

Changes in Cementation of Reef Building Oysters Transitioning from Larvae to Adults.

Oysters construct extensive reef communities, providing food, protection from storms, and healthy coastlines. We still do not have a clear picture of how these animals attach to surfaces. Efforts described herein provide the first examination of adhesion at the transition from free swimming larvae to initial substrate attachment, through metamorphosis, and on to adulthood. Two different bonding systems were found to coexist. Larvae use an organic, hydrated glue that persists while the animal progresses into the juvenile phase, at which point a very different adhesive emerges. Juveniles bond with an organic-inorganic composite system, positioning the organic component for maximum adhesion by residing between the animal and substrate. Beyond understanding our marine environment, these insights may aid efforts in aquaculture, reef restoration, and adhesive design.

Highly Selective Colorimetric and Luminescence Response of a Square-Planar Platinum(II) Terpyridyl Complex to Aqueous TcO4(-).

Molecular recognition of an aqueous pertechnetate (TcO4(-)) anion is fundamentally challenging partly due to the charge-diffuse nature of this anion, which hampers design of new technologies for its separation and detection. To address this gap, simple salts of transition metal complexes that undergo a distinct spectroscopic change upon exposure to aqueous anions were explored. The Pt(II) complex [Pt(tpy)Br]SbF6 (tpy = 2,2';6',2″-terpyridine) undergoes a dramatic color change and intense luminescence response upon TcO4(-) uptake due to concomitant enhancement of Pt···Pt interactions. The spectroscopic response was highly selective and quantitative for aqueous TcO4(-) among other competing anions. Complementary Raman spectroscopy and microscopy techniques, structural determination, and theoretical methods were employed to elucidate the mechanism of this response at the molecular level.

Structural and compositional characterization of the adhesive produced by reef building oysters.

Oysters have an impressive ability to overcome difficulties of life within the stressful intertidal zone. These shellfish produce an adhesive for attaching to each other and building protective reef communities. With their reefs often exceeding kilometers in length, oysters play a major role in balancing the health of coastal marine ecosystems. Few details are available to describe oyster adhesive composition or structure. Here several characterization methods were applied to describe the nature of this material. Microscopy studies indicated that the glue is comprised of organic fiber-like and sheet-like structures surrounded by an inorganic matrix. Phospholipids, cross-linking chemistry, and conjugated organics were found to differentiate this adhesive from the shell. Symbiosis in material synthesis could also be present, with oysters incorporating bacterial polysaccharides into their adhesive. Oyster glue shows that an organic-inorganic composite material can provide adhesion, a property especially important when constructing a marine ecosystem.

Between red and yellow: evidence of intermediates in a vapochromic Pt(II) salt.

[Pt(tpy)Cl]ClO4·H2O (1·H2O) changes from red to yellow upon dehydration due to increased Pt···Pt distances. Spectroscopic, diffraction, gravimetric and calorimetric data demonstrate the presence of intermediates during hydration and dehydration which signifies surprising mechanistic complexity in the vapochromic response.

Solid-state materials for anion sensing in aqueous solution: highly selective colorimetric and luminescence-based detection of perchlorate using a platinum(II) salt.

The PF(6)(-) salt of a platinum(II) complex changes from yellow to red and becomes intensely luminescent upon exposure to aqueous ClO(4)(-). The response is remarkably selective. Spectroscopic changes are consistent with anion exchange resulting in shortening of the intramolecular PtPt distances between the square planar cations.

Superheated water chromatography-nuclear magnetic resonance spectroscopy and mass spectrometry of vitamins.

The water-soluble vitamins, pyridoxine, riboflavin, and thiamine, were separated by reversed-phase liquid chromatography using hot or superheated water as the mobile phase and were detected using a range of detectors, including ultraviolet and fluorescence spectroscopy and mass spectrometry. By using deuterium oxide as the eluent, direct on-line nuclear magnetic resonance spectra could be obtained with minimal spectral interference from the mobile phase. Some of the compounds showed deuterium exchange of alkyl-protons when separated at high temperatures.