Switchable absorbers

Lumophores other than hydrocarbons have been incorporated into the aminoalkyl aromatic family of ionically switchable luminescent devices. For instance, metal-loporphyrin systems such as have been used to good advantage. These cases absorb and emit at wavelengths as long as 596 and 650 nm, respectively. Such red-shifted systems are particularly attractive for monitoring ion movements in... 

Photoisomerizations can often occur by several different mechanisms. Systems that isomerize via a controlled mechanism are potential candidates for molecular machines [184]. Energy in the form of light is absorbed and converted to controlled mechanical force on the molecular scale. Examples of a mono-directional rotor [185, 186], a switchable rotor [187], and a molecular shuttle [188] have been demonstrated. These systems are light-controlled, but there are also examples of systems which control molecular motion based on electro- and/or chemical modulation, such as the threading/imthreading of (pseudo)rotaxanes [189-196]. 

Fig. 10A, B. A redox-switchable supramolecular system based on charge-transfer interactions which can be read by spectroscopic means. A Redox switching of the host compound 22. B Redox switching of the guest 24. The absorbance spectra in A and B are adapted from [42] and [43], respectively, with permission...

Fig. 15A-C. Mechanical switching in catenanes. A The individual rings of catenanes may be unsymmetrical. A [2]catenane with two distinct sites on each ring may exist in four different states. B A switchable catenane based on the competitive binding of TTF and dioxynaph-thalene residues on one ring inside the cavity of the second ring. The TTF moiety is bound preferentially in the reduced state, but is repelled in the oxidized state and replaced with the dioxynaphthalene unit. C A proton-switchable [2]catenane. The phenanthroline units in the rings of 37 form a complex around H+, but, when H+ is not present, a charge-transfer complex is formed between the viologen units in one ring and the dioxynaphthalene unit in the other. The absorbance spectra are adapted from [64] with permission...

Syntheses, electrochemical and spectroscopic (UV, Vis, NIR, and EPR) properties of [ MoCl(Tp )(NO) 2( -i-L)] containing two-redox active Mo(Tp ) units linked by a conjugated bridging ligand L have been reported by McCleverty and others. Some of these complexes exhibit intense, redox-switchable absorbance in the near-IR region.75... 

Fig. 7.20 The three optical states of a liquid electrolyte Cd-Mg switchable mirror (a) shiny metallic at positive voltage ( 2V), (b) strongly absorbing at 1 V and (c) transparent and insulating at negative voltages (—2V). In this device the Gd-Mg layer deposited on a glass substrate is used as the...

A unique electrically conductive material, distinguished by a long term stability and fast switchable electrophysical properties, is poly(3,4-ethylenedioxythiophene) with specific electrical conductivities up to 30 S cm" and more. It can be used for antistatic coatings (see section 10.3), as electrode material for solid state capacitors (see section 10.5), for electrochromic devices (see section 10.8) and as IR absorber [11]. 

Within the last five years or so, several studies have been performed on dynamic (switchable) microwave absorbers. Studies at the US Navy s China Lake, CA facility, although highly secretive, are thought to involve metallic grids deposited on high microwave loss substrates such as Teflon on which a CP layer is deposited... 

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