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1
Nintendo eShop - Chromophore: The Two Brothers Director
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::2014/06/09::
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2
Chromophore-Chromophore Interactions (3.5)
Chromophore-Chromophore Interactions (3.5)
::2010/01/20::
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Chromophore, Chromophore Definition, Explanation of Chromophores
Chromophore, Chromophore Definition, Explanation of Chromophores
::2012/11/18::
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Chemistry of Colors
::2012/11/09::
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Pigments and Chromophores in Nature (3.7)
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CGI Animated Audio-Visual Performance HD: "Chromophore" by - Paul Prudence
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How to Pronounce Chromophore
How to Pronounce Chromophore
::2014/01/31::
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Chromophore Electro Plurality
Chromophore Electro Plurality
::2012/03/26::
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Chromophore [Red Nebula]
Chromophore [Red Nebula]
::2011/04/22::
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Chromophore [Blue Nebula]
Chromophore [Blue Nebula]
::2011/04/24::
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Happy Chromophore in Bacteriorhodopsin
::2011/05/22::
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Chromophore: Color Blind Aid System DEMO
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Chromophore [Imploding Star]
::2011/04/24::
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Synthesis of Polarity-Indicating Chromophore
Synthesis of Polarity-Indicating Chromophore
::2012/11/22::
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CHROMOPHORE
CHROMOPHORE
::2014/02/02::
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Chromophore
Chromophore
::2014/04/27::
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Auxochromes, Auxochromes Definition
Auxochromes, Auxochromes Definition
::2012/11/16::
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CHROMOPHORE
CHROMOPHORE
::2011/01/28::
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How to Pronounce Chromophores
How to Pronounce Chromophores
::2014/01/31::
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Protein Methods 2010 - Dilutions with Chromophores (no audio)
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Intercalation into DNA studied by X-ray crystallography
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Laser Skin Whitening at ONLYAESTHETICS
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Alash Ensemble Track 3 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
Alash Ensemble Track 3 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
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Aerosol Detector for any Nonvolatile or Semivolatile Analyte
::2013/03/20::
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Alash Ensemble Track 2 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
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Alash Ensemble Track 6 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
Alash Ensemble Track 6 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
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Alash Ensemble Track 1 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
Alash Ensemble Track 1 (Tuvan Throat Singing) at the University of Chicago (Nov. 2013)
::2013/11/27::
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Molecular Chromophores for Next-Generation Solar Photon Harvesting, Andrew Ferguson - O+P 2013
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Photofragmentation & Photoelimination Reactions
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Corona ultra RS Detector
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3D stereoscopic audiovisual performance   YouTube
3D stereoscopic audiovisual performance YouTube
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5 certamen djs villasequilla vocalista alba 2 by cesar cuenca dj
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Imploads mountain home
::2012/10/24::
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Data transmission on 7452Khz
::2012/04/28::
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cut
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::2014/06/12::
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Paul Prudence - 2/3- AV showcase #4: Generative & Live Coding @ Juno-Videohackspace kick-off
Paul Prudence - 2/3- AV showcase #4: Generative & Live Coding @ Juno-Videohackspace kick-off
::2012/12/19::
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From Wikipedia, the free encyclopedia
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A chromophore is the part of a molecule responsible for its color.[1] The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls within the range of the visible spectrum. Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state.

In biological molecules that serve to capture or detect light energy, the chromophore is the moiety that causes a conformational change of the molecule when hit by light.

Chemical structure of beta-carotene. The eleven conjugated double bonds that form the chromophore of the molecule are highlighted in red.

Conjugated pi-bond system chromophores[edit]

Conjugated chromophore that straightens in response to a photon γ (light), of the correct wavelength: 11-cis-retinal becomes all-trans-retinal

In the conjugated chromophores, the electrons jump between energy levels that are extended pi orbitals, created by a series of alternating single and double bonds, often in aromatic systems. Common examples include retinal (used in the eye to detect light), various food colorings, fabric dyes (azo compounds), pH indicators, lycopene, β-carotene, and anthocyanins. Various factors in a chromophore's structure go into determining at what wavelength region in a spectrum the chromophore will absorb. Lengthening or extending a conjugated system with more unsaturated (multiple) bonds in a molecule will tend to shift absorption to longer wavelengths. Woodward-Fieser rules can be used to approximate ultraviolet-visible maximum absorption wavelength in organic compounds with conjugated pi-bond systems.

Some of these are metal complex chromophores, which contain a metal in a coordination complex with ligands. Examples are chlorophyll, which is used by plants for photosynthesis and hemoglobin, the oxygen transporter in the blood of vertebrate animals. In these two examples, a metal is complexed at the center of a tetrapyrrole macrocycle ring: the metal being iron in the heme group (iron in a porphyrin ring) of hemoglobin, or magnesium complexed in a chlorin-type ring in the case of chlorophyll. The highly conjugated pi-bonding system of the macrocycle ring absorbs visible light. The nature of the central metal can also influence the absorption spectrum of the metal-macrocycle complex or properties such as excited state lifetime.[2][3][4] The tetrapyrrole moiety in organic compounds which is not macrocyclic but still has a conjugated pi-bond system still acts as a chromophore. Examples of such compounds include bilirubin and urobilin, which exhibit a yellow color.

Auxochrome[edit]

An auxochrome is a functional group of atoms attached to the chromophore which modifies the ability of the chromophore to absorb light, altering the wavelength or intensity of the absorption.

Halochromism in chromophores[edit]

Halochromism occurs when a substance changes color as the pH changes. This is a property of pH indicators, whose molecular structure changes upon certain changes in the surrounding pH. This change in structure affects a chromophore in the pH indicator molecule. For example, phenolphthalein is a pH indicator whose structure changes as pH changes as shown in the following table:

Structure Phenolphthalein-low-pH-2D-skeletal.svg Phenolphthalein-mid-pH-2D-skeletal.svg
pH 0-8.2 8.2-12
Conditions acidic or near-neutral basic
Color name
colorless
pink to fuchsia
Color

In a pH range of about 0-8, the molecule has three aromatic rings all bonded to a tetrahedral sp3 hybridized carbon atom in the middle which does not make the π-bonding in the aromatic rings conjugate. Because of their limited extent, the aromatic rings only absorb light in the ultraviolet region, and so the compound appears colorless in the 0-8 pH range. However as the pH increases beyond 8.2, that central carbon becomes part of a double bond becoming sp2 hybridized and leaving a p orbital to overlap with the π-bonding in the rings. This makes the three rings conjugate together to form an extended chromophore absorbing longer wavelength visible light to show a fuchsia color.[5] At pH ranges outside 0-12, other molecular structure changes result in other color changes; see Phenolphthalein for details.

See also[edit]

External links[edit]

References[edit]

  1. ^ IUPAC Gold Book Chromophore
  2. ^ Gouterman, M. (1978) Optical spectra and electronic structure of porphyrins and related rings. In Dolphin, D. (ed.) The porphyrins. Academic Press, New York. Volume III, Part A, pp 1-165
  3. ^ Scheer, H. (2006) An overview of chlorophylls and bacteriochlorophylls: biochemistry, biophysics, functions and applications. Advances in Photosynthesis and Respiration, vol 25, pp 1-26
  4. ^ Shapley, P. (2012) Absorbing light with organic molecules. http://butane.chem.uiuc.edu/pshapley/GenChem2/B2/1.html
  5. ^ UV-Visible Absorption Spectra
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