Abstract: Heterocyclic compounds incorporating a [1,3]oxazine ring may be used to make chromogenic materials. These molecules switch from a colorless state to a colored form upon addition of either acid or base. In both instances, the [1,3]oxazine ring opens in response to the pH change forming an indolium cation, after the addition of acid, or a phenolate anion, after the addition of base. Alternatively, the switch may occur in response to a change in electrical current or potential or a change in temperature. Chromophores absorb in the visible region of the electromagnetic spectrum. Hence, their formation translates into the appearance of color. These processes are fully reversible and the original colorless state can be regenerated by switching the pH back to neutral. Thus, these halochromic compounds can be used to develop displays, filters, indicators, lenses, sensors, switches, or windows able to switch their color in response to pH changes.

Abstract: We have designed a molecular switch based on the photoinduced opening and thermal closing of a [1,3]oxazine ring. A substituted [1,3]oxazine compound described as having a general (i.e., unsubstituted) structure with fused indoline and benzooxazine fragments such that they share a common bond in the [1,3]oxazine compound: (i) the bond connecting positions 1 and 2 of the indoline fragment and (ii) the bond connecting positions 2 and 3 of the benzooxazine fragment. Irradiation by light of suitable wavelength and intensity of this photochromic compound induces cleavage of a [C—O] bond of the [1,3]oxazine ring to form a phenolate chromophore. The photogenerated (e.g., colored) isomer may revert thermally to the starting (e.g., colorless) oxazine. Alternatively, the switch may be between isomers of the compound that absorb at different wavelengths. Reversible coloration of silica or polymeric materials and switching optical signals may involve many cycles of interconversion between different colored states.

Abstract: A chromogenic oxazine compound for the colorimetric detection of cyanide was designed. Indeed, the [1,3]oxazine ring of our compound opens to form a phenolate chromophore in response to cyanide. The heterocyclic com-pound may be comprised of fused benzooxazine and indoline rings: wherein R1 is an alkyl (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl), a substituted alkyl, a cycloalkyl (e.g., cyclopentyl, cyclohexyl), a substituted cycloalkyl, an aryl (e.g., phenyl), or a substituted aryl and R2 is a chromophore (e.g., nitroso, nitro, azo dyes). This quantitative chromogenic transformation permits the detection of micromolar concentrations of cyanide in water. Furthermore, our chromogenic oxazine is insensitive to the presence of large concentrations of fluoride, chloride, bromide or iodide anions, which are generally the principal interferents in the colorimetric detection of cyanide.

Abstract: Semiconductor quantum dots are becoming valuable analytical tools for use in biomedical applications. Indeed, their unique properties offer the opportunity to design luminescent probes for imaging and sensing with unprecedented performance. In this context, we have identified operating principles to transduce supramolecular association of complementary receptor-ligand binding pairs into enhancement or suppression in the luminescence of sensitive quantum dots. Thus, complementary receptor-ligand binding pairs can be identified with luminescence measurements relying on our design logic. In fact, we have demonstrated with a representative example that our protocol can be adapted to signal receptor-ligand binding.

Abstract: We have designed a molecular switch based on the photoinduced opening and thermal closing of a [1,3]oxazine ring. A substituted [1,3]oxazine compound described as having a general (i.e., unsubstituted) structure with fused indoline and benzooxazine fragments such that they share a common bond in the [1,3]oxazine compound: (i) the bond connecting positions 1 and 2 of the indoline fragment and (ii) the bond connecting positions 2 and 3 of the benzooxazine fragment. Irradiation by light of suitable wavelength and intensity of this photochromic compound induces cleavage of a [C—O] bond of the [1,3]oxazine ring to form a phenolate chromophore. The photogenerated (e.g., colored) isomer may revert thermally to the starting (e.g., colorless) oxazine. Alternatively, the switch may be between isomers of the compound that absorb at different wavelengths. Reversible coloration of silica or polymeric materials and switching optical signals may involve many cycles of interconversion between different colored states.

Abstract: Heterocyclic compounds incorporating a [1,3]oxazine ring may be used to make chromogenic materials. These molecules switch from a colorless state to a colored form upon addition of either acid or base. In both instances, the [1,3]oxazine ring opens in response to the pH change forming an indolium cation, after the addition of acid, or a phenolate anion, after the addition of base. Alternatively, the switch may occur in response to a change in electrical current or potential or a change in temperature. Chromophores absorb in the visible region of the electromagnetic spectrum. Hence, their formation translates into the appearance of color. These processes are fully reversible and the original colorless state can be regenerated by switching the pH back to neutral. Thus, these halochromic compounds can be used to develop displays, filters, indicators, lenses, sensors, switches, or windows able to switch their color in response to pH changes.

Abstract: We have designed a molecular switch based on the photoinduced opening and thermal closing of a [1,3]oxazine ring. A substituted [1,3]oxazine compound described as having a general (i.e., unsubstituted) structure with fused indoline and benzooxazine fragments such that they share a common bond in the [1,3]oxazine compound: (i) the bond connecting positions 1 and 2 of the indoline fragment and (ii) the bond connecting positions 2 and 3 of the benzooxazine fragment. Irradiation by light of suitable wavelength and intensity of this photochromic compound induces cleavage of a [C—O] bond of the [1,3]oxazine ring to form a phenolate chromophore. The photogenerated (e.g., colored) isomer may revert thermally to the starting (e.g., colorless) oxazine. Alternatively, the switch may be between isomers of the compound that absorb at different wavelengths. Reversible coloration of silica or polymeric materials and switching optical signals may involve many cycles of interconversion between different colored states.

Abstract: Semiconductor quantum dots are becoming valuable analytical tools for use in biomedical applications. Indeed, their unique properties offer the opportunity to design luminescent probes for imaging and sensing with unprecedented performance. In this context, we have identified operating principles to transduce supramolecular association of complementary receptor-ligand binding pairs into enhancement or suppression in the luminescence of sensitive quantum dots. Thus, complementary receptor-ligand binding pairs can be identified with luminescence measurements relying on our design logic. In fact, we have demonstrated with a representative example that our protocol can be adapted to signal receptor-ligand binding.

Abstract: A chromogenic oxazine compound for the colorimetric detection of cyanide was designed. Indeed, the [1,3]oxazine ring of our compound opens to form a phenolate chromophore in response to cyanide. The heterocyclic com-pound may be comprised of fused benzooxazine and indoline rings: wherein R1 is an alkyl (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl), a substituted alkyl, a cycloalkyl (e.g., cyclopentyl, cyclohexyl), a substituted cycloalkyl, an aryl (e.g., phenyl), or a substituted aryl and R2 is a chromophore (e.g., nitroso, nitro, azo dyes). This quantitative chromogenic transformation permits the detection of micromolar concentrations of cyanide in water. Furthermore, our chromogenic oxazine is insensitive to the presence of large concentrations of fluoride, chloride, bromide or iodide anions, which are generally the principal interferents in the colorimetric detection of cyanide.

Abstract: We identified a mechanism to detect chemical changes with a modified semiconductor nanoparticle (e.g., an oxazine-adsorbed CdSe—ZnS core-shell quantum dot). Our strategy is based on the chemical transformation of chromo-genie ligands adsorbed on the surface of a quantum dot. This activates an energy transfer pathway from the quantum dot to the adsorbed chromogenic ligands, which causes a change (e.g., increase or decrease) in a characteristic of fluorescent emission (e.g., intensity or lifetime). Thus, modified quantum dots acting through this mechanism can efficiently transduce a chemical event or occurrence into a change in optical signal. Our design can be adapted to signal chemical changes by a diversity of target analytes and, thus, it can be used to develop other fluorescent chemosensors based on the unique properties of quantum dots.

Abstract: An optical storage medium 100 has a multilayer structure that includes a photochromic layer 110 having a thermally-stable photochromic compound, and a fluorescent layer 120 having a fluorescent compound. The photochromic compound is transformable between a first form and a second form. The fluorescent compound has an excitation wavelength centered in a region that is not substantially absorbed by the second form of the photochromic compound, and an emission wavelength that is absorbed by the first form and not absorbed by the second form.

Abstract: Volatile and non-volatile solid state molecular switching devices which are electrically addressable and may be used in memory cells, routing circuits, inverters and field programmable devices which may or may not be designed to exhibit diode behavior. The molecular switching devices include certain [2] catenanes as bistable molecules which are sandwiched between two switch terminals. The switches are extremely small and have dimensions which range from several microns down to a few nanometers.