Receptors ferrocene-based

C-H functionalizations, 10, 115 ferrocene-based receptors for, 12, 486-487 hydrophobic, via zinc compounds, 9, 97 phosphine-containing, supports for, 12, 700-701 a-Amino acids... 

Ferrocene-based bisphosphanes, in hydrogenations, 10, 10 Ferrocene-based receptors anion receptors, 12, 476 cation receptors, 12, 466 for neutral guest species, 12, 483 Ferrocene-based sensors, screen-printed, in biosensing,... 

Metal carbonyl monoanions, with trivalent Group 13 element halides, 3, 347, 3, 357 Metal carbynes, Fe-containing, 6, 325 Metal-catalyzed cycloadditions, alkenyl- and alkynylboron compounds, 9, 180 Metal cation receptors characteristics, 12, 466 ferrocene-based, 12, 466 Pt- and Au-based receptors, 12, 471 types, 12, 473 Metal chalcogenides... 

Many of the receptors synthesised interact with a wide variety of anions however, selectivity has been introduced to these systems. Ferrocene-based systems have been shown to detect aqueous phosphate [99] and sulphate [100] ions. Ferrocene boronic acid has been shown to associate with fluoride ion with much stronger binding than to chloride,bromide and other anions [101]. 

Molecules 9-13 are a selection of ferrocene-based receptors which include secondary amide groups for the hydrogen bonding of anions [ 12,13]. Measured... 

Roy and co-workers have recently described a ferrocene-based receptor for amino acids. Strong 1 1 binding of 127 for amino acids in MeCN/H20 (55/45) mixtures at pH = 7.2 was observed by UV/VIS, fluorescence, electrochemistry, isothermal calorimetry (ITC), and NMR. Glu and Asp, which exist in their anionic form at this pH, were found to have the greatest affinity for the receptor (iTa(127 Glu) = 98 x and... 

The receptor 73, based on an azaferrocenophane structure bearing two urea groups as linkers between the redox active (ferrocene) and fluorescent (naphthalene) signalling subimits, also shows both fluorescent and electrochemical sensing of fluoride [51]. On addition of excess fluoride it displays an enhancement factor of 13 in the naphthalene emission bands at 362 and 380 nm in DMF solution and a cathodic shift of the ferrocene/ferrocenium couple of 190 mV in DMSO electrolyte solution. 

The accessible ferrocene/ferrocenium redox couple of ferrocene has led to its frequent use in electrochemical anion sensors. The chemical and structural similarity between ferrocene and cobaltocenium has meant that receptors based on these complexes often share the same design. The most relevant difference is that the ferrocene derivatives are neutral (until oxidised to ferrocenium),have no inherent electrostatic interaction with anions and therefore their complexes with anions exhibit lower stability constants. 

Receptor 93 incorporates a zinc porphyrin backbone with four ferrocene amides [65]. This shares the design of the cobaltocenium receptor 4, except that now a zinc atom occupies the centre of the porphyrin. The Lewis acid metal centre provides an additional binding site for anion recognition. In dichloro-methane solution no significant anion-induced shifts in the lH NMR signals of the amide protons were seen in the free-base precursor of 93, whereas the... 

Ferrocene units appended with secondary amides have also been used for anion recognition (113-115) (231). Being neutral, unlike cobaltocenium based systems, these receptors have no inherent electrostatic attraction making the NMR stability constants much lower in magnitude than for the analogous cobaltocenium systems. Electrostatic interactions can, however, be switched on by oxidation of ferrocene to ferrocenium and consequently these molecules show interesting electrochemical effects and have a potential as amperometric anion sensors. Of interest to this development of sensor technology were the novel results of electrochemical competition experiments. These results demonstrated... 

---