Biological detection and tagging using tailorable, reactive, highly fluorescent chemosensors.

This program was focused on the development of a fluorogenic chemosensor family that could tuned for reaction with electrophilic (e.g. chemical species, toxins) and nucleophilic (e.g. proteins and other biological molecules) species. Our chemosensor approach utilized the fluorescent properties of well-known berberine-type alkaloids. In situ chemosensor reaction with a target species transformed two out-of-plane, weakly conjugated, short-wavelength chromophores into one rigid, planar, conjugated, chromophore with strong long wavelength fluorescence (530-560 nm,) and large Stokes shift (100-180 nm). The chemosensor was activated with an isourea group which allowed for reaction with carboxylic acid moieties found in amino acids

(E)-2-{Eth­yl[4-(4-nitro­phenyl­diazen­yl)phen­yl]amino}ethyl anthracene-9-carboxyl­ate

The crystal structure of the title compound, C31H26N4O4, displays a trans conformation for the nitro­phenyl­diazenyl portion of the mol­ecule. Packing diagrams indicate that weak C—H⋯O hydrogen bonds, likely associated with a strong dipole moment present in the mol­ecule, dictate the arrangement of mol­ecules in the crystal structure

(E)-4-[(4-Nitro­phen­yl)diazen­yl]phenyl anthracene-9-carboxyl­ate

In the title compound, C27H17N3O4, the azo group displays a trans conformation and the dihedral angles between the central benzene ring and the pendant anthracene and nitro­benzene rings are 82.94 (7) and 7.30 (9)°, respectively. In the crystal structure, weak C—H⋯O hydrogen bonds, likely associated with a dipole moment present on the mol­ecule, help to consolidate the packing

(E)-2-{Eth-yl[4-(4-nitro-phenyl-diazen-yl)phen-yl]amino}ethyl anthracene-9-carboxyl-ate.

The crystal structure of the title compound, C(31)H(26)N(4)O(4), displays a trans conformation for the nitro-phenyl-diazenyl portion of the mol-ecule. Packing diagrams indicate that weak C-H⋯O hydrogen bonds, likely associated with a strong dipole moment present in the mol-ecule, dictate the arrangement of mol-ecules in the crystal structure

Color detection using chromophore-nanotube hybrid devices.

We present a nanoscale color detector based on a single-walled carbon nanotube functionalized with azobenzene chromophores, where the chromophores serve as photoabsorbers and the nanotube as the electronic read-out. By synthesizing chromophores with specific absorption windows in the visible spectrum and anchoring them to the nanotube surface, we demonstrate the controlled detection of visible light of low intensity in narrow ranges of wavelengths. Our measurements suggest that upon photoabsorption, the chromophores isomerize from the ground state trans configuration to the excited state cis configuration, accompanied by a large change in dipole moment, changing the electrostatic environment of the nanotube. All-electron ab initio calculations are used to study the chromophore-nanotube hybrids and show that the chromophores bind strongly to the nanotubes without disturbing the electronic structure of either species. Calculated values of the dipole moments support the notion of dipole changes as the optical detection mechanism

(E)-4-[(4-Nitro-phen-yl)diazen-yl]phenyl anthracene-9-carboxyl-ate.

In the title compound, C(27)H(17)N(3)O(4), the azo group displays a trans conformation and the dihedral angles between the central benzene ring and the pendant anthracene and nitro-benzene rings are 82.94 (7) and 7.30 (9)°, respectively. In the crystal structure, weak C-H⋯O hydrogen bonds, likely associated with a dipole moment present on the mol-ecule, help to consolidate the packing

Assuring ultra-clean environments in microsystem packages : irreversible and reversible getters.

A new generation of irreversible, chemically reacting getters specifically targeted toward assuring the integrity of the local environment within microsystem packages were developed and evaluated. These reactive getters incorporate volatile species into a polymer through covalent bonds, thus producing a non-volatile product. These reactive getters will be combined with getters that rely on absorption media (e.g. zeolites and high surface area carbon fibers) to scavenge non-reactive species, like solvents. Our getter systems will rely on device packaging to limit exchange between the microsystem and the global environment. Thus, the internal getters need only provide local environmental control within the microsystem package. A series of experiments were conducted to determine uptake rates and capacities absorption and reactive-based getters. Diffusion rates through the binder used to hold the getter particles together were also investigated. Getters were evaluated in environments with a saturated headspace and with a limited amount of the volatile species of interest. One- and two-dimensional numerical models and analysis techniques have been developed and used to predict the transport of contaminant species within a representative microsystem package consisting of an open gas-filled volume adjacent to a polymer layer containing embedded particles of getter. The two-dimensional model features explicit representation of the individual getter particles while the one-dimensional treatment assumes a homogeneous distribution of getter material within the getterlpolymer layer. Example calculations illustrate the dependence of getter performance on reaction rates, polymer diffusivity, and getter particle volume fraction. In addition, the model is used to deduce surface reaction rates, solid phase diffusivities, and maximum-loading densities by least-squares fitting of model predictions to measured histories of gas-phase contaminant concentration and getter weight gain

Metathesis depolymerization for removable surfactant templates

Current methodologies for the production of meso- and nanoporous materials include the use of a surfactant to produce a self-assembled template around which the material is formed. However, post-production surfactant removal often requires centrifugation, calcination, and/or solvent washing which can damage the initially formed material architecture(s). Surfactants that can be disassembled into easily removable fragments following material preparation would minimize processing damage to the material structure, facilitating formation of templated hybrid architectures. Herein, we describe the design and synthesis of novel cationic and anionic surfactants with regularly spaced unsaturation in their hydrophobic hydrocarbon tails and the first application of ring closing metathesis depolymerization to surfactant degradation resulting in the mild, facile decomposition of these new compounds to produce relatively volatile nonsurface active remnants