This contribution describes the concept of a new high precision micro- and nano-force measurement facility. It consists of a measuring disc-pendulum and an identical reference disc-pendulum for the reduction of thermal and seismic noise. According to the theoretical calculations in the paper, the disc-pendulums with electrostatic stiffness reduction and electrostatic deflection compensation should allow quasi-static forces to be measured in the range <10−5 N with a force resolution of 10−12 N.

A new differential nanoforce facility, based on a disc-pendulum with electrostatic stiffness reduction and an electrostatic force compensation for the measurement of horizontal forces in the range below 1 µN, is presented. First measurements in air over an averaging time of 50 s show a noise level of the facility of 42 pN. The method and the results of measuring the light pressure of a red He-Ne laser with a power of 7 mW (F L = 47 pN) are presented. The force measurement uncertainty of the device is below 5%, for a force to be measured of 1 nN and a measuring duration of 50 s.

The reaction of [B12H11NH3]-, the amino derivative of the closo-dodecaborate anion, with aldehydes in methanol in the presence of catalytic amounts of alkali gives N-protonated Schiff bases [B12H11NHCHR]- (R = C6H5, 2-C6H4OMe, 4-C6H4OMe, 4-C6H4SMe, 4-C6H4NMe2, 4-C6H4NHCOMe, 4-C6H4CN, 4-C6H4Br, 4-C6H4Cl, 3,4-C6H3O2CH2, 1-C10H7, 2-C10H7, CHCHMe, CHCHPh). Reduction of the Schiff bases with NaBH4 in aqueous 2-propanol gives quantitatively the corresponding monoalkylamino derivatives [B12H11NH2CH2R]- (R = 2-C6H4OMe, 3,4-C6H3O2CH2, 4-C6H4NHCOMe, 4-C6H4CN). closo-Dodecaborate derivatives containing amino, carboxy, and isothiocyanate functions on aromatic rings, [B12H11NH2CH2C6H4-4-NH2]-, [B12H11NH2CH2C6H4-4-COOH]-, and [B12H11NH2CH2C6H4-4-NCS]-, were prepared. Functionalized derivatives of the [B12H12]2- anion can be used in BNCT and as a linker for iodination and astatination of biomolecules for radioimmunodetection and for radioimmunotherapy. The structures of Schiff bases (Bu4N)[B12H11NHCHC6H4-4-NMe2]*CHCl3 (I) and (Bu4N)[B12H11NHCHC6H4-2-OMe] (II) were determined by single-crystal X-ray diffraction. I crystallizes in the monoclinic space group P21/c with Z = 4 and unit cell dimensions a = 11.465(6) Å, b = 21.314(7) Å, c = 16.625(6) Å, β = 101.38(3)°. Crystals II belong to the monoclinic space group P21/c system, a = 10.282(2) Å, b = 20.272(5) Å, c = 17.052(3) Å, β = 105.31(2)°, Z = 4. The trans configuration of the protonated imino group was established (B−N = 1.517(7) and 1.525(4) Å, N−Cim = 1.274(6) and 1.274(3) Å, Cim−Car = 1.421(7) and 1.437(4) Å, for I and II, respectively). A strong intramolecular hydrogen bond between the imine hydrogen and the methoxy oxygen in the ortho position of the benzene ring (N···O = 2.714(4) Å, N−H = 0.93(2) Å, HN···O = 1.98(2) Å, N−H···O = 135(2)°) was found in II.

The 3D micro probe is based on a silicon boss-membrane with piezo-resistive transducers, which enable the measurement of the deflections of the probing pin and, simultaneously, the forces in all three dimensions. The development of a 3D silicon boss-membrane micro probe poses the problem of different stiffnesses in the Z- and X-, Y-directions. In general the ratio of these stiffnesses is approximately 30. A novel design (the so-called twin design) makes the achievement of equal stiffness possible in the three orthogonal probing directions of the 3D micro probe. The twin design is based on two parallel single silicon boss-membranes attached to each other. An analytical model for the calculation of the mechanical properties of the twin design is submitted. The developed analytical model describes the deformations of the membranes if the probe pin is deflected, and also the nonlinear mechanical properties of the twin design 3D micro probe. A comparison and an analysis of the experimental and theoretical results of the twin design investigation were carried out.

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