A comparison of the solid structures of three novel trinuclear sandwich Pt 2 Pb systems (NBu 4 ) 2 [{Pt(C≡CTol) 4 } 2 Pb(OH 2 ) 2 ] 1, [{Pt(bzq)(C≡CPh) 2 } 2 Pb] 2, and (NBu 4 ) [{Pt(bzq)) with that of the previously reported (NBu 4 ) 2 [{Pt(C 6 F 5 ) 4 } 2 Pb] 5 showed that the local environment of Pb II is highly sensitive to the nature of the anionic platinate(II) precursors. The photoluminescence (PL) studies of all 1-5 complexes revealed a dependence of PL on the structure type. Thus, complexes 1 and 5 exhibit metal centered emissions (1, 497 nm, 77 K; 5, 539 nm, φ ) 0.43, 298 K) related to the linear ( 5) or bent (1 Pt-Pb-Pt 149.9°) trinuclear entities. However, in complexes 2-4, that have unprecedented Pb II • • • η 1 (C≡CR) bonding interactions and very short Pt • • • Pb and Pt • • • Pt distances, the emissive state in solid state (77 K) is attributed to a 3 MLM′CT [Pt(1)π(C≡CR)fPt(2)/Pb(sp)π*(C≡CR)] state mixed with some ππ* excimeric character in neutral complexes 2 (R ) Ph) and 3 (R ) C 6 H 4 -CF 3 -4), and in the case of the adduct (NBu 4 )[{Pt(bzq)(C≡CC 6 H 4 -CF 3 -4) 2 } 2 Pb(O 2 ClO 2 )] 4 modified also by Pb II • • • O (O 2 ClO 2 -) contacts.chain. [25][26][27][28][29][30][31][32][33][34][35][36] Furthermore, the alkynyl ligands exhibit a very good π(η 2 ) coordinating capability, and we [37][38][39][40][41][42][43][44][45] and others [46][47][48][49][50][51][52][53] have demonstrated that the luminescence behavior is strongly influenced by perturbation of the electron density of the CtC unit through η 2 • • • metal alkynyl bonding and also by metallophilic interactions. [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Homo and heteropolynuclear aggregates and clusters based on closed and/or subclosed-shell (d 8 , d 10 , d 10 s 2 ) metallic interactions [54][55][56][57][58] have also been studied as interesting emitters. [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] The presence of strong metallophilic interactions determines their structures and is often cited as an essential factor of their remarkable photophysical properties. [54][55][56][57][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] The arrangement of the metals and, in particular, the type of metals and coligands have a profound effect on the photophysical behavior of the resulting polynuclear systems. 61,74 Therefore, the controlled formation of novel polymetallic systems of the above metals and the study of their structure property correlations are of great importance in designing functional materials. Within this field, compared to the numerous reports involving polar M-Tl I54,

We report a series of luminescent sandwich-type clusters [Pt2 Pb2 (C≡CR)8] (R=Tol, 1; C6 H4 OMe-3, 2; C6 H4 OMe-4, 3) with a dynamic Pt2 Pb2 metallic core, which is key to their intriguing stimuli-responsive photophysical properties. The solvent-free solids 1-3 display an orange emission ascribed to charge transfer from Pt-alkynyl fragments to a delocalized orbital with mixed Pt2 Pb2 /C≡CR nature, with a predominant lead contribution and Pb⋅⋅⋅Pb bonding character ((3) MLCCT/(3) IL). They exhibit mechanical, color, and luminescence changes that are reversible and perceivable with the naked eye, which are attributed to small inter- and intramolecular structural modifications induced by gentle grinding. Interestingly, 1 and 2 also exhibit remarkable and fast reversible vapochromic responses to donor solvent vapors (acetone, THFMe-2: yellow; NCMe: green, vs. dry solids: orange). The structures of 1(acetone)2 ⋅2(Me2 CO), 2(acetone)3 , and 2(THFMe-2)2 allow the vapochromic responses to be ascribed to the fast creation/disruption of solvate clusters [Pt2 Pb2 (C≡CR)8 Sx] (x≥2), with concomitant electronic and geometrical modifications within the Pt2 Pb2 core, which are easily accessible through a slight change in the stereochemical activity of the lone pair. The binding of one (or two) solvent molecules to Pb(2+) increases the Pb⋅⋅⋅Pb separation in the metallic core, causing a destabilization of the target orbital and larger energy gaps of the transitions. All the solvates exhibit remarkable rigidochromism upon a decrease in temperature, which is also associated with the gradual increase in the transannular Pb⋅⋅⋅Pb separation, as revealed by X-ray crystallography of 1(acetone)2 at different temperatures. Investigation of the crystal lattice of 1⋅CH2 Cl2 and 3⋅2 CH2 Cl2 further suggests that the lack of vapor stimuli response of complex 3 could be attributed to the presence of competitive additional secondary intermolecular Pb⋅⋅⋅O(OMe) contacts, which give rise to a more compact network built up from extended chains of clusters.

The evaluation of the relationship between the vibro-acoustical signals generated by friction stir spot welding (FSSW) process with its parameters and stages such as torque, dwell time, and tool rotation speed, is developed in this work. A dissimilar lap-joint was conducted using pure copper and AA1050 H24 aluminium alloy. The vibro-acoustical signals in Z and Y directions, and torque applied by the tool during the process have been acquired by the instrument NI USB-9234. The characterisation in the time and frequency domains of the vibro-acoustical signals has been performed in order to correlate them with the stages of processing and tool torque. The analysis has confirmed that the vibro-acoustical signals were significantly affected by changes in process forces and can thus be used as a non-destructive method for process monitoring, optimisation tasks, and control of FSSW process.

A new class of heteroleptic blue emitter anion, [trans-Pt(C[triple bond, length as m-dash]CTol)(2)(CN)(2)](2-), has been prepared and successfully used in the assembling of luminescent supramolecular heterometallic PtTl(2) and PtPb(2) species.

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