Syntheses and crystal structures of 2,2,5-trimethyl-1,3-dioxane-5-carb-oxy-lic acid and 2,2,5-trimethyl-1,3-dioxane-5-carb-oxy-lic anhydride.

In 2,2,5-trimethyl-1,3-dioxane-5-carb-oxy-lic acid, C8H14O4, the carboxyl group occupies an equatorial position on the 1,3-dioxane ring. In the crystal, O-H⋯O hydrogen bonds form chains of mol-ecules, which are linked into a three-dimensional network by C-H⋯O hydrogen bonds. The asymmetric unit of 2,2,5-trimethyl-1,3-dioxane-5-carb-oxy-lic anhydride, C16H26O7, consists of two independent mol-ecules, which are linked by C-H⋯O hydrogen bonds. In the crystal, these units are connected into corrugated layers two mol-ecules thick and parallel to the ab plane by additional C-H⋯O hydrogen bonds.

Iodine-Containing Mass-Defect-Tuned Dendrimers for Use as Internal Mass Spectrometry Calibrants.

Calibrants based on synthetic dendrimers have been recently proposed as a versatile alternative to peptides and proteins for both MALDI and ESI mass spectrometry calibration. Because of their modular synthetic platform, dendrimer calibrants are particularly amenable to tailoring for specific applications. Utilizing this versatility, a set of dendrimers has been designed as an internal calibrant with a tailored mass defect to differentiate them from the majority of natural peptide analytes. This was achieved by incorporating a tris-iodinated aromatic core as an initiator for the dendrimer synthesis, thereby affording multiple calibration points (m/z range 600-2300) with an optimized mass-defect offset relative to all peptides composed of the 20 most common proteinogenic amino acids. Graphical abstract ᅟ.

Investigation of Lysine-Functionalized Dendrimers as Dichlorvos Detoxification Agents.

Lysine-containing polymers have seen broad application due to their amines' inherent ability to bind to a range of biologically relevant molecules. The synthesis of multiple generations of polyester dendrimers bearing lysine groups on their periphery is described in this report. Their hydrolytic stabilities with respect to pH and time, their toxicity to a range of cell lines, and their possible application as nano-detoxification agents of organophosphate compounds are all investigated. These zeroth-, first-, and second-generation water-soluble dendrimers have been designed to bear exactly 4, 8, and 16 lysine groups, respectively, on their dendritic periphery. Such monodisperse bioactive polymers show potential for a range of applications including drug delivery, gene delivery, heavy metal binding, and the sequestration of organic toxins. These monodisperse bioactive dendrimers were synthesized using an aliphatic ester dendritic core (prepared from pentaerythritol) and protected amino acid moieties. This library of lysine-conjugated dendrimers showed the ability to efficiently capture the pesticide dichlorvos, confirming the potential of dendrimer-based antidotes to maintain acetylcholinesterase activity in response to poisoning events.