Colors state

A compromise between coloration and economics in commercial ionic liquid production is therefore necessary. Since chromatographic decoloration steps are known and relatively easy to perform (see Section 2.2.3), we would not expect there to be a market for a colorless ionic liquid, if the same substance can be made in a slightly colored state, but at a much lower price. 

Chemistry is concerned with the properties of matter, its distinguishing characteristics. A physical property of a substance is a characteristic that we can observe or measure without changing the identity of the substance. For example, a physical property of a sample of water is its mass another is its temperature. Physical properties include characteristics such as melting point (the temperature at which a solid turns into a liquid), hardness, color, state of matter (solid, liquid, or gas), and density. A chemical property refers to the ability of a substance to change into another substance. For example, a chemical property of the gas hydrogen is that it reacts with (burns in) oxygen to produce water a chemical property of the metal zinc is that it reacts with acids to produce hydrogen gas. The rest of the book is concerned primarily with chemical properties here we shall review some important physical properties. 

Oxide materials in the colored state are usually mixed-valence compounds with a variable range of composition. The color usually arises from low-energy intraband electronic transitions. 

No. Type Chemical formula Color state Intradimer6 Interdimer angle (deg.) (deg.) (deg.)f Reference ... 

Fig. 17.3 Chromatic transition of crystalline W03/CNT sheets, (a) Original state appear yellow colored states after applying -1.0 V for (b) 5 s, (c) 15 s and (d) 30 s. Reprinted with permission from [20], Copyright 2012, The Royal Society of Chemistry.

The effect of electron transfer between tungsten oxide and titanium oxide is also important in photochromatic applications. In an excellent study of aqueous sols. He et al. analyze the electronic structure of the tungsten oxide-titanium oxide system, finding that titanium oxide can catalyze the generation of W+. This state is a colored state and can be generated from WO3 WH2O by the following reactions ... 

Electrochromic materials of interest can be classified according to three types of color change (1) from a bleached state (transparent) to a colored state, (2) between two colored states, and (3) between several colored states, if more than two redox states are accessible. This behavior is called polyelectrochromic... 

Metal-oxide-based electrochromic systems are especially interesting for the development of electrochromic windows because they mostly switch from a transparent state to a dark colored state [38,39]. In addition, their relatively slow response times are acceptable for this kind of application, possibly even preferable from an aesthetic point of view. Again, W03 has seen the most use in the development of actual devices. Several different deposition techniques have been applied. For example, a prototype electrochromic window based on W03 with reasonable dimensions (0.7 X 1 m) has been assembled that reduces light transmission by a factor of 4 in its colored state [28]. 

When the colored state of poly(308) is heated at high temperature above 100°C, it is expected to return to the colorless state to give poly(307). The color disappeared completely within 10 min at 150°C to reproduce poly (307). 

Compound Color/state m.p, (°C) Sublim. temp. (°C) Solubility 1 Ref. 

The three quark color states are restricted to the color singlet, 1=1, which together with the fermion antisymmetry principle leads to requirement that the flavor-ordinary spin space must be totally symmetric i. e., I I I I This, in turn, leads to the following relationships between the flavor space and the ordinary spin space ... 

In order for the color state to persist for an extended time, a charge separation of the photogenerated ions must be produced such as that in a photosynthetic process in biological systems. Also, the rate of reverse electron transfer can be retarded by the presence of an external field. 

---