Dyestuffs fluorescence

Decomposition Ozonisation Very effective, side effect disinfection but need of special equipment, probability of damaging dyestuffs, fluorescent brighteners and sensitive fibres like nylon... 

Besides their biological activity, some other important industrial applications of triazoles and benzotriazoles are known, including dyestuffs, fluorescent compounds, optical bright-eners, corrosion inhibitors, photostabilizers and agrochemicals. Some selected applications are described in the following sections. 

Uses Leveling agent, dispersant for dyeing polyester fibers with disperse dyestuffs, fluorescent whitening of polyester fibers with disperse FWAs and dyeing the polyester component of polyester/cellulosic blends by the HT process Features Prevents filtration of dyestuffs does not inc. the AOX content of waste-water pumpable resist, to acids, alkali, salts, hard water Properties YIsh.-brn. Iiq. readily sol. in water dens. 1.0 g/ml (20 C) pH 4,0 (10%)... 

Many hydrazones and azines are colored and useful as dyestuffs. Examples are 2-hydroxynaphthazine, a yellow fluorescent dye (Lumogen LT Bright Yellow), and the pyridon—azino—quinone class of red-violet dyes. Numerous hydrazine derivatives are antioxidants and stabilizers by virtue of their reducing and chelating powers. 

Fluorescent Dyestuffs. Very few dyes are of use in making daylight-fluorescent products. Of the dyes discovered up to 1920, only the brilliant ted and salmon dyes of the rhodamine and rosamine classes ate used in fluorescent materials in the 1990s. The first of these, Rhodamine B, was discovered in 1877. Fluorescence excited by both uv and visible light components in daylight was formally recognized as a notable property of certain dyed fabrics by the 1920s (1). 

Table 1. Important Dyestuffs for Daylight-Fluorescent Pigments...

Recent pigment technology has yielded a wide range of products which ate much mote specialized for individual end use applications. New polymers have been combined with improved dyestuffs to yield fluorescent pigments with better performance properties and economics, and more desirable environmental characteristics. 

Daylight fluorescent pigments (qv) are considered to be nontoxic. Since they are combinations of polymers and dyestuffs, the combined effect of the ingredients must be taken into account when considering the net toxic effect of these materials. Table 5 gives results of laboratory animal toxicity tests of standard modified melamine—formaldehyde-type pigments, the Day-Glo A Series, and the products recommended for plastic mol ding, Day-Glo Z-series. 

Optical brighteners are colourless fluorescent dyestuffs that absorb in the near UV (350-390 nm) and fluoresce in the violet to blue region of the spectrum (425-445 nm). 

Fluorimetry is generally used if there is no colorimetric method sufficiently sensitive or selective for the substance to be determined. In inorganic analysis the most frequent applications are for the determination of metal ions as fluorescent organic complexes. Many of the complexes of oxine fluoresce strongly aluminium, zinc, magnesium, and gallium are sometimes determined at low concentrations by this method. Aluminium forms fluorescent complexes with the dyestuff eriochrome blue black RC (pontachrome blue black R), whilst beryllium forms a fluorescent complex with quinizarin. 

There is typically little or no toxicology or metabolism data available for even moderately comphcated boron-based compounds. An interesting exception is the collection of tetrahydro-3a,4a,4-diazabora-j-indacenes (8) <71SRI83> structurally related to the BODIPY fluorescent dyestuffs. Rather well characterized, these compounds are stable to both water and alcohols at 23 C and undergo reversible salt formation with HCl and NaOH. Compound 8b, teimed Myborin, was evaluated for its toxicity <75MI434>. The LDj values of 69.5 mg/kg i.p., 180 mg/kg p.o., and 420 mg/kg s.c. in the mouse reveal it to have moderate toxicity. 

It has been common knowledge that conventional Raman spectroscopy has failed in attempting to analyze dyes or dyestuffs. Most of the common dyes fluoresce intensely when excited in the visible. However, with the introduction of FT-Raman, the characterization of dyes has improved dramatically. Raman spectra are obtained, which are free of fluorescence and/or resonance effects. One such study involving the investigation of low levels of dyestuffs in acrylic fibers is presented (4). 

A series of dyestuffs have been reported which contain the pyrido[2,3-p]-l,2,4-triazine and pyrido[4,3-e]-1,2,4-triazine nuclei. These compounds have been used to dye a number of fibres fluorescent yellow shades <74GEP(0)2417916>. Another series of polyheterocyclic dyestuffs which contain a pyridotriazine moiety have been patented as fast yellow dyes especially for synthetic fibres <75GEP(0)2355967>. Amongst a number of the compounds prepared as dyestuffs were several 1H-pyrido-l,3,4-thiadiazines. The compounds were used to dye polyester fibres fast shades of yellow <77USP4025510>. 

Oxadiazoles have a wide variety of uses, in particular as biologically active compounds in medicine and in agriculture, as dyestuffs, UV absorbing and fluorescent materials, heat-resistant polymers and scintillators. Reviews of the relevant literature prior to 1965 are available <66AHC(7)183,62HC(17)263>. 

In the 2-quinolylmethanes and -amines, the di-cis configuration can be fixed by quaternization with compounds having two active atoms, e.g., CH2I2.46,47 The rigid ring structures formed in this way cause the intense fluorescence of these compounds which are known as quinoline red dyestuffs (e.g., pyridine red, quinoline red, phenan-... 

Ila and Ilia (Section V, B, 2), and IVa (Section V, A, 2) of the periodic system, and with transition metals (Section V,B, 1). All these metal compounds and those quinoline red dyestuffs which exist only in the form 25 by introduction of suitable substituents (e.g., Fig. 13) have analogous absorption and fluorescence spectra, with pronounced vibrational structures, and many other similar properties. This... 

In addition to symmetry restrictions on electronic transitions, there are restrictions caused by the necessity of overlap in space of molecular orbitals for the electron in its initial and final states. Where this overiap is small, for example in n -> jt transitions in carbonyl compounds, the electronic integral in Eq. (1) is diminished. The allowedness of a transition F expressed as an oscillator strength can be summarised as in (4) by a series of factors, f, which relate in turn to spin, (s), overlap (o), p (parity), sy (symmetry), and which have the following approximate values fg = 10 , fo = 10 , fp = 10 , fgy = 10 -10 , where F is the oscillator strength of a fully allowed transition. For fluorescence then (fg = 1), values of Icr extend from 10 s for a fully allowed transition, typical say of dyestuffs, through lO s for... 

---