An Organic Metal/Silver Nanoparticle Finish on Copper for Efficient Passivation and Solderability Preservation

For the first time, a complex formed by polyaniline (in its organic metal form) and silver has been deposited on copper in nanoparticulate form. When depositing on Cu pads of printed circuit boards it efficiently protects against oxidation and preserves its solderability. The deposited layer has a thickness of only nominally 50 nm, containing the Organic Metal (conductive polymer), polyaniline, and silver. With >90% (by volume), polyaniline (PAni) is the major component of the deposited layer, Ag is present equivalent to a 4 nm thickness. The Pani–Ag complex is deposited on Cu in form of about 100 nm small particles. Morphology, electrochemical characteristics, anti-oxidation and solderability results are reported

Structure of thioaromatic self-assembled monolayers on gold and silver

Self-assembled monolayers (SAMs) formed from thiophenol, 1,1‘-biphenyl-4-thiol, 1,1‘;4‘,1‘ ‘-terphenyl-4-thiol, and anthracene-2-thiol on polycrystalline Au and Ag were characterized by X-ray photoelectron spectroscopy and angle-resolved near-edge X-ray absorption fine structure spectroscopy. With the exception of the poorly defined thiophenol film on Au, all thioaromatic molecules were found to form highly oriented and densely packed SAMs on both substrates. The molecular orientation and orientational order of the adsorbed thioaromatic molecules depends on the number of aromatic rings, the substrate, and the rigidity of the aromatic system. The molecules, which on average are slightly inclined with respect to the surface normal, show a less tilted orientation with increasing length of the aromatic chain, and as observed for aliphatic SAMs, they exhibit smaller tilt angles on Ag than on Au. However, the difference in the tilt angles for aromatic SAMs on Au and Ag is smaller than that observed in the aliphatic films. A comparison of the monolayers formed from p-terphenylthiol and anthracenethiol films suggests that a higher molecular rigidity has only a slight effect on the final molecular orientation within the respective SAMs

Ge tetramer structure of the p ( 2 2 × 4 2 ) R 45 ° surface reconstruction of Ge/Ag(001): A surface x-ray diffraction and STM study

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Reduced and Oxidized Forms of the Pt-Organometallic Version of Polyaniline

This work represents an effort to synthesize all four forms of polyaniline (PANI) in its organometallic versions. Polymers containing substituted 1,4-benzoquinone diimine or 1,4-diaminobenzene units in the backbone exhibiting the general structure (C CC6H4-N=C6X4=N-C6H4C C-PtL2) and (C CC6H4NH-C6X4NHC6H4C C-PtL2) along with the corresponding model compounds (C CC6H4-N=C6X4=N-C6H4C C)-(PtL2Cl)(2) and (C CC6H4NH-C6X4-NHC6H4C C)-(PtL2Cl)(2) (L = PBu3; X = H, F, Cl) were synthesized. The polymers and corresponding model compounds were characterized (including H-1 and P-31 NMR, IR, mass spectra, elemental analysis, and X-ray structure determinations) and investigated for their redox properties in the absence and in the presence of acid. Their optical properties, including ns transient spectroscopy were also investigated. These properties were interpreted through density functional theory (DFT) and time-dependent DFT (TDDFT) computations. These materials are found to be oligomers (GPC) with thermal stability (TGA) reaching 350 degrees C. The greatest stabilities were found in the cases with X = F. Using a data bank of 8 X-ray structures of diimine derivatives, a relationship between the C=N bond distance and the dihedral angle between the benzoquinone ring and the flanking phenyl planes is noted. As the size of the substituent X on the benzoquinone center increases, the degree of conjugation decreases as demonstrated by the C=N bond length. The largest dihedral angles are noted for X = Cl. These polymers exhibit drastic chemical differences when X is varied (X = H, F, Cl). The completely reduced polymer (C CC6H4NH-C6H4-NHC6H4C C-PtL2) (i.e., X = H) was not chemically accessible whereas in the cases of X = F, Cl, these materials were obtained and represent the first examples of fully reduced organometallic versions of PANI (i.e., leucoemaraldine). For the (C CC6H4-N=C6X4=N-C6H4C C-PtL2) polymers, the completely oxidized form for X = H was isolated (pemigraniline), but for X = F and Cl, only the largely reduced mixed-valence form (i.e., emaraldine) was obtained via chemical routes. In acidic solutions, the chemically accessible polymer for X = H, (C CC6H4-N=C6H4=N-C6H4C C-PtL2), exhibits two chemically reversible waves indicating that the reduced form (C CC6H4NH-C6H4-NHC6H4C C-PtL2) can be generated. The absorption spectra of the highly colored diimine-containing species exhibit a broad charge transfer band (assigned based on DFT calculations (B3LYP); C6H4C C-PtL2-C CC6H4 -> N=C6X4=N) in the 450-800 nm window red shifting according X = H -> Cl -> F, consistent with their relative inductive effect. The largest absorptivity is measured for X = H because this polymer is fully oxidized whereas for the cases where X = F and Cl, these polymers exists in the mixed valence form. The ns transient absorption spectra of two polymers (X = F; reduced and mixed-valence polymers) were measured. The triplet excited state in the mixed-valence polymer is dominated by the reduced diamine residue and the T-1-T-n absorption of the diimine is entirely quenched