COLORANT CHEMISTRY From Prisms to Phthalocyanines Jeffery H. - PowerPoint PPT Presentation

COLORANT CHEMISTRY From Prisms to Phthalocyanines Jeffery H. Banning PhD Principal Scientist 3D SYSTEMS CORP. Wilsonville, Oregon I. ADDITIVE / SUBTRACTIVE COLORATION: II. CLASSIFICATION OF COLORANTS: BASED ON THE ELECTRONIC ORIGIN OF THE COLORANT*: (A) Acyclic and Cyclic Polyene Chromogens. (B) Donor-Acceptor Chromogens. (C) Cyanine-Type Chromogens. III. INDUSTRIAL EXPERIENCES WITH MODIFYING COLORANTS [Yes, you can do it too!!] * Griffiths, J.: Colour and Constitution of Organic Molecules. Academic Press 1976 1

Primary Colors for Additive Coloration Primary Colors for Subtractive Coloration Maxwell's arrangement - additive coloration - e.g., phosphors of a color TV Superimposed dyes - subtractive coloration - e.g., artists paint palatte, color printer, etc Kirk-Othmer Encyclopedia of Chemical Technology - 3rd Ed., Vol 6, page 619 Kirk-Othmer Encyclopedia of Chemical Technology - 3rd Ed., Vol 6, page 619 See: "The Fifteen Causes of Color (see table 3 and pp.860-875)" From the chapter on Color (pp. 841-876) Kirk-Othmer Encyclopedia of Chemical Technology Kurt Nasau, Consultant 4th Edition, Volume 6 John Wiley and Sons, Inc. 1993 ISBN 0-471-52674-6 Also: The Causes of Color by Kurt Nassau 1980 SCIENTIFIC AMERICAN, INC p.124 2 https://www.physics.utoronto.ca/~phy189h1/Causes%20of%20Color%20scientificamerican1080-124.pdf

ADDITIVE COLORATION: SUN "WHITE LIGHT" (Contains "all" wavelengths of visible light) 3

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ADDITIVE COLORATION: SUN Red: Longest "WHITE LIGHT" wavelength, (Contains all wavelengths of light) lower energy Yellow Green A prism can be used to "separate" all of the different wavelengths of "visible" light as Green-Blue shown above. Blue Violet: Shortest wavelength, highest energy 5

6 R R FILTER E E T T L L I I F F

Examples seen with: phosphors of the “old” cathode ray tube based colored TV set, LEDs, OLEDs or any emissive based display today. 7

ADDITIVE COLORATION : Three monochromatic radiations are selected so that they are well separated sectors can be combined to make the color in the center (ex. Green, blue and red to make white) 8

ADDITIVE COLORATION : Two monochromatic radiations from any pair of flanking sectors can be combined to make the color in the between them (ex. Green and red to make yellow ) 9

SUBTRACTIVE COLORATION: "WHITE LIGHT" (Contains all wavelengths of light) The eye SUN perceives this complex mixture as Greenish-Blue ORANGE . FILTER Greenish-Blue light selectively filtered out Most colors that are prevalent throughout our environment arise from what is known as the subtractive color mixing process . In additive coloration we saw that the mixing of all the wavelengths (of colors) in the visible spectrum give "white light". However, if one of the components of "white light" (one wavlength, or even a narrow band of wavelengths) is removed, the color registered by the eye is the complementary color of the radiation removed (despite the fact that the light falling on the eye is still a complex mixture of wavelengths). Example shown above: If sunlight is passed through a filter that removes a band of wavelengths in the region of 485 nm (i.e., Greenish-blue light) the eye will perceive the complementary color of greenish-blue -- i.e., orange (vice verse would be true: if only orange wavelength removed would appear 10 greenish-blue).

The eye perceives this complex mixture as BLUE . 11

SUBTRACTIVE COLORATION: The eye perceives this complex "WHITE LIGHT" (Contains all mixture as wavelengths of light) YELLOW . SUN Blue light selectively absorbed (filtered out) lemon Example shown above: When "white light" from a lightbulb or the sun hits the lemon, the pigments in the lemon absorb (filter) light (band of wavelengths) corresponding to the blue region. Hence, the remaining wavelengths of "white light" (less the blue) hit the retina of the eye. The eye will perceive the complementary color of blue - namely yellow 12

SUBTRACTIVE COLORATION: The eye "WHITE LIGHT" perceives this (Contains all complex wavelengths of light) mixture as GREEN . SUN Red and violet light selectively absorbed (filtered out) green pepper Example shown above: When "white light" from a lightbulb or the sun hits the " green " pepper, the pigments in the pepper absorb (filter) light corresponding to the purple region. But, no wavelength corresponding to purple exists. Instead wavelengths corresponding to red and violet (both flanking the purple region) are absorbed (i.e., effectively filtered) and the remaining wavelengths will hit the retina of the eye. 13 The eye will perceive the complementary color of red and violet as green .

SUBTRACTIVE COLORATION: "WHITE LIGHT" The eye (Contains all perceives this wavelengths of light) 8-ball as BLACK . SUN ) t u o d e r e t l i f ( d e b r o s b a y l e v i t c e l e s s i t h g i l L L A 8-ball Example shown above: When "white light" from a lightbulb or the sun hits the " black " 8-ball, the pigments in the ball absorb (filter) light corresponding to all wavelengths (i.e., all light is absorbed). Black is the absence of color (wavelengths) hitting the retina of the eye. The eye will perceive the absence of any color (light of any wavelength) hitting it as black. 14

SUBTRACTIVE COLORATION: The eye perceives this "WHITE LIGHT" complex (Contains all wavelengths of light) mixture as WHITE . SUN ) d e r e t l i f ( d e b r o s b a e r a t h g i l f o s h t g n e l e v a w o N White Object (baseball) Example shown above: When "white light" from a lightbulb or the sun hits the white baseball, no light absorbs (or is filtered). Instead, all of the wavelengths are reflected and will hit the retina of the eye. The eye will perceive this as white. 15

The eye perceives this lemon as BLACK . all light absorbed (filtered out) Example shown above: When "white light" from a lightbulb or the sun is filtered so that only the single wavelength of light corresponding to blue is able to hit the lemon, the pigments in the lemon absorb (filter) light in the blue region. Hence, no remaining wavelengths of visible light are left to hit the retina of the eye (i.e., all wavelengths of visible light are absorbed by the lemon) 16 The eye will perceive this situation - with no reflected visible light as black

SUBTRACTIVE COLORATION: glass cuvette with yellow The eye "WHITE LIGHT" dye dissolved (Contains all in colorless perceives this wavelengths of light) solvent complex mixture as YELLOW . SUN The wavelength corresponding to blue ligh t is absorbed by the dye in solution and not "seen" by the eye (detector) The remaining wavelengths of visible light are transmitted through the dye in solution and "seen" by the eye (detector) Example shown above: When "white light" from a lightbulb or the sun hits the cuvette containing a dye, the dye in solution absorb (filter) light (band of wavelengths) corresponding to the blue region. Hence, the remaining wavelengths of "white light" (less the blue) hit the retina of the eye. The eye will perceive the complementary color of blue - namely yellow 17

SUBTRACTIVE COLORATION: (With Cyanine Dye) "WHITE LIGHT" Xanthene (Contains all (Rhodamine B) wavelengths of light) H 3 CH 2 C CH 2 CH 3 N O N SUN H 3 CH 2 C CH 2 CH 3  * CO 2 - NBMO The visible absorption band corresponds to the excitation of an electron from the HOMO (which is the NBMO in this case) into one of the LUMO (which is the vacant  * orbital) of the chromogen. The Green radiation matches “exactly” the energy necessary to excite and electron from the HOMO to the LUMO The eye will perceive the complementary color of green - namely Magenta Example shown above: When "white light" hits the dye, the dye absorbs light corresponding to the green region . Hence, the remaining wavelengths of "white light" hit (are transmitted to) the retina of the eye. 18

 max A = log (1/T) 19

SUBTRACTIVE COLORATION: (With Cyanine Dye) - FLUORESCENCE The eye perceives this complex mixture as MAGENTA "WHITE LIGHT" Xanthene (Contains all with an (Rhodamine B) wavelengths of light) ORANGISH fluorescene H 3 CH 2 C CH 2 CH 3 N O N SUN H 3 CH 2 C CH 2 CH 3  * CO 2 - NBMO H 3 CH 2 C CH 2 CH 3 N O N H 3 CH 2 C CH 2 CH 3  * CO 2 - NBMO  * (LUMO)  * (LUMO) light heat NBMO (HOMO) NBMO (HOMO) Fluorescence Radiationless transition (occurs when an excited electron drops back to its ground (occurs when an excited electron drops back to state - emmitting a photon of light. Usually this emmision of its ground state without the emission of light and radiation is of a longer wavelength usually involves transfer of heat to solvent) than the radiation that was absorbed) Note: 20 only the lowest vibrational energy levels are shown - the associated vibrational levels are not shown