Design of a Cooper pair box electrometer for application to solid-state and astroparticle physics

We describe the design and principle of operation of a fast and sensitive electrometer operated at millikelvin temperatures, which aims at replacing conventional semiconducting charge amplifiers in experiments needing low back-action or high sensitivity. The electrometer consists of a Cooper Pair box (CPB) coupled to a microwave resonator, which converts charge variations to resonance frequency shifts. We analyze the dependence of the sensitivity on the various parameters of the device, and derive their optimization. By exploiting the nonlinearities of this electrometer, and using conventional nanofabrication and measurement techniques, a charge sensitivity of a few $10^{- 7} e / \sqrt{Hz}$ can be achieved which outperforms existing single charge electrometers.Comment: 13 pages, 7 figure

Novel Method for Grafting Alkyl Chains onto Glassy Carbon. Application to the Easy Immobilization of Ferrocene Used as Redox Probe

Primary alkyl iodides (RI) have been found to react with a cathodically charged glassy carbon surface at potentials more negative than −1.7 V vs Ag/AgCl. In aprotic solvents, this reaction results in grafting of the alkyl chains onto carbon. It is proposed that the process corresponds to the cathodic charge of graphitized and fullerenized zones present in carbon followed by a displacement reaction (analogous to a nucleophilic attack) toward alkyl iodides. This new mode of grafting is applied to the immobilization of ferrocene used as an electrochemical probe. The present work points out the reaction of ω-iodoalkylferrocenes and quantifies the level of grafting of alkyl chains via this promising method for modification of carbon surfaces. Coverage levels were found to be high, reaching the apparent surface concentrations of 8 × 10^–9 mol cm^–2. These large values are explained on the basis of swelling of the interface provoked by progressive charging of the carbon surface via insertion of tetraalkylammonium cations concomitantly with the substitution process. Alkylferrocene layers deposited onto carbon were found to be chemically and electrochemically stable

Efficient Anodic Allylation and Benzylation of Carbons Using Allyl and Benzyl Trimethylsilanes

An easy process for allylation and benzylation of different carbon materials, primarily of glassy carbon, in acetonitrile solutions containing tetraalkyammonium salts is described. The method relies on the capability of C­(sp²) zones of glassy carbon (graphite and fullerene-like inclusions) to be anodically charged at potentials >1.5 V versus Ag/AgCl to form electrophilic centers reacting with substituted trimethylsilanes RSiMe₃. Great propensity of the trimethylsilyl group (TMS⁺) to act as a cationic leaving group facilitates electrophilic reactions of the charged anodic surface with R-carrying silylated precursors, permitting efficient grafting of a large variety of R groups. The present preliminary work focuses only on the efficient grafting of benzyl and allyl moieties

Diastereoselective <i>ortho</i>-Metalation of a Chiral Ferrocenylphosphonic Diamide and Its Organotin Derivatives

The syntheses of the enantiopure ferrocenylphosphonic diamide (3a<i>R</i>,7a<i>R</i>)-2-ferrocenyl-3a,4,5,6,7,7a-octahydro-1,3-dimethyl-1,3,2-benzodiazaphosphole 2-oxide ((<i>R</i>,<i>R</i>)-FcP­(O)­(DMCDA), (<i>R</i>,<i>R</i>)-<b>1</b>) and its enantiomer (<i>S</i>,<i>S</i>)-FcP­(O)­(DMCDA) ((<i>S</i>,<i>S</i>)-<b>1</b>) are reported. Their ortho lithiation and subsequent treatment with Ph₃SnCl selectively provided the corresponding tetraorganotin derivatives FcP­(O)­(DMCDA)­SnPh₃ ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b> and (<i>S,S,S</i>_P)-<b>2</b>) in a diastereoselective ratio of 88:12. The absolute configuration of the major diastereomer was confirmed by single-crystal X-ray diffraction analysis. DFT calculations revealed that kinetic effects of the lithiation step cause the high diastereoselectivity of the formation of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b>. Further functionalization of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b> with elemental iodine gave the enantiopure organotin iodide derivatives FcP­(O)­(DMCDA)­SnI_<i>n</i>Ph_3–<i>n</i> ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b>:, <i>n</i> = 1; (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>4</b>, <i>n</i> = 2, (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>5</b>, <i>n</i> = 3). The triorganotin fluoride FcP­(O)­(DMCDA)­SnFPh₂ ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>6</b>) was obtained by the reaction of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b> in dichloromethane with aqueous KF solution. The reaction of the compound (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b> with silver triflate gave the <i>R</i>,<i>R</i>,<i>R</i>_P-configurated triorganotin triflate FcP­(O)­(DMCDA)­SnPh₂(OTf) (<b>7</b>), which exists as a contact ion pair in the solid state and shows dynamic behavior in solution. The reaction of <b>7</b> with Ph₃PO afforded the corresponding organotin salt [FcP­(O)­(DMCDA)­SnPh₂(OPPh₃)]­[OTf] ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>8</b>)

Diastereoselective <i>ortho</i>-Metalation of a Chiral Ferrocenylphosphonic Diamide and Its Organotin Derivatives

The syntheses of the enantiopure ferrocenylphosphonic diamide (3a<i>R</i>,7a<i>R</i>)-2-ferrocenyl-3a,4,5,6,7,7a-octahydro-1,3-dimethyl-1,3,2-benzodiazaphosphole 2-oxide ((<i>R</i>,<i>R</i>)-FcP­(O)­(DMCDA), (<i>R</i>,<i>R</i>)-<b>1</b>) and its enantiomer (<i>S</i>,<i>S</i>)-FcP­(O)­(DMCDA) ((<i>S</i>,<i>S</i>)-<b>1</b>) are reported. Their ortho lithiation and subsequent treatment with Ph₃SnCl selectively provided the corresponding tetraorganotin derivatives FcP­(O)­(DMCDA)­SnPh₃ ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b> and (<i>S,S,S</i>_P)-<b>2</b>) in a diastereoselective ratio of 88:12. The absolute configuration of the major diastereomer was confirmed by single-crystal X-ray diffraction analysis. DFT calculations revealed that kinetic effects of the lithiation step cause the high diastereoselectivity of the formation of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b>. Further functionalization of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>2</b> with elemental iodine gave the enantiopure organotin iodide derivatives FcP­(O)­(DMCDA)­SnI_<i>n</i>Ph_3–<i>n</i> ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b>:, <i>n</i> = 1; (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>4</b>, <i>n</i> = 2, (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>5</b>, <i>n</i> = 3). The triorganotin fluoride FcP­(O)­(DMCDA)­SnFPh₂ ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>6</b>) was obtained by the reaction of (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b> in dichloromethane with aqueous KF solution. The reaction of the compound (<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>3</b> with silver triflate gave the <i>R</i>,<i>R</i>,<i>R</i>_P-configurated triorganotin triflate FcP­(O)­(DMCDA)­SnPh₂(OTf) (<b>7</b>), which exists as a contact ion pair in the solid state and shows dynamic behavior in solution. The reaction of <b>7</b> with Ph₃PO afforded the corresponding organotin salt [FcP­(O)­(DMCDA)­SnPh₂(OPPh₃)]­[OTf] ((<i>R</i>,<i>R</i>,<i>R</i>_P)-<b>8</b>)

Novel Tin-Containing Crown Ether Substituted Ferrocenophanes as Redox-Active Hosts for the Ditopic Complexation of Lithium Chloride

The synthesis is reported of the crown ether substituted tin-containing ferrocenophanes fc­(SiMe₂CH₂)₂Sn­(X)­CH₂CH­(CH₂OC₂H₄OCH₂)₂ (<b>1</b>, X = Ph; <b>2</b>, X = I; <b>3</b>, X = Cl; <b>4</b>, X = F) and of the ditopic complex <b>3</b>·LiCl. The compounds were characterized by multinuclear NMR spectroscopy, single-crystal X-ray diffraction analysis, and cyclic voltammetry. DFT calculations revealed important two-electron stabilization in <b>3</b> and <b>4</b> due to intramolecular O→Sn coordination that is absent in <b>2</b>

Novel Tin-Containing Crown Ether Substituted Ferrocenophanes as Redox-Active Hosts for the Ditopic Complexation of Lithium Chloride

The synthesis is reported of the crown ether substituted tin-containing ferrocenophanes fc­(SiMe₂CH₂)₂Sn­(X)­CH₂CH­(CH₂OC₂H₄OCH₂)₂ (<b>1</b>, X = Ph; <b>2</b>, X = I; <b>3</b>, X = Cl; <b>4</b>, X = F) and of the ditopic complex <b>3</b>·LiCl. The compounds were characterized by multinuclear NMR spectroscopy, single-crystal X-ray diffraction analysis, and cyclic voltammetry. DFT calculations revealed important two-electron stabilization in <b>3</b> and <b>4</b> due to intramolecular O→Sn coordination that is absent in <b>2</b>

Extending Chirality in Group XIV Metallatranes

The syntheses of the racemic amino alcohol rac-N­(CH2CMe2OH)­(CMe2CH2OH)­(CH2CHMeOH) (L22’1*H3, 2) and its representative N­(CH2CMe2OH)­(CMe2CH2OH)­(CH2C­(R)­HMeOH) (L22’1RH3, 3) with the stereogenic carbon center being R-configured are reported. Also reported are the stannatranes L22’1*SnOt-Bu (4) L22’1RSnOt-Bu (6) and germatranes L22’1*GeOEt (5) and L22’1RGeOEt (7) as well as the trinuclear tin oxocluster [(μ3-O)­(μ3-O-t-Bu)­{SnL22’1R}3] (8). NMR and IR spectroscopy, electrospray ionization mass spectrometry (ESI MS), and single crystal X-ray diffraction analysis characterize these compounds. Computational studies accompany the experimental work and help understand the diastereoselectivity observed in the course of the metallatrane syntheses

Simultaneous Control of Emission Localization and Two-Photon Absorption Efficiency in Dissymmetrical Chromophores

The aim of the present work is to demonstrate that combined spatial tuning of fluorescence and two-photon absorption (TPA) properties of multipolar chromophores can be achieved by introduction of slight electronic chemical dissymmetry. In that perspective, two model series of structurally related chromophores have been designed and investigated. One is based on rod-like quadrupolar chromophores bearing either two identical or different electron-donating (D) end groups and the other on three-branched octupolar chromophores built from a trigonal donating moiety bearing identical or different acceptor (A) peripheral groups. The influence of the electronic dissymmetry is investigated by combined experimental and theoretical studies of the linear and nonlinear optical properties of dissymmetrical chromophores compared to their symmetrical counterparts. In both types of systems (i.e., quadrupoles and octupoles), experiments and theory reveal that excitation is essentially delocalized and that excitation involves synchronized charge redistribution (i.e., concerted intramolecular charge transfer) between the different D and A moieties within the multipolar structure. In contrast, the emission stems only from a particular dipolar subunit bearing the strongest D or A moiety due to fast excitation localization after excitation, prior to emission. Hence, control of emission characteristics (polarization and emission spectrum), can be achieved, in addition to localization, by controlled introduction of electronic dissymmetry (i.e., replacement of one of the D or A end-groups by a slightly stronger D′ or A′ unit). Interestingly, slight dissymmetrical functionalization of both quadrupolar and octupolar compounds does not lead to significant loss in TPA responses and can even be beneficial due to the spectral broadening and peak position tuning that it allows. This study thus reveals an original molecular engineering route allowing TPA enhancement in multipolar structures, due to concerted core-to-periphery or periphery-to-core intramolecular charge redistribution upon excitation, while providing for control of emission localization. Such a route could be extended to more intricate (dendritic) and multipolar (3D) systems