Neutralization reactions of the appropriate precursors (NBu(4))[Pt(bzq)(C[triple bond, length as m-dash]C-R)(2)] and (NBu(4))[Pt(Cinsertion markN)(CN)(2)] (Cinsertion markN = bzq, ppy) with Tl(I) salts afford [{PtTl(bzq)(C[triple bond, length as m-dash]C-R)(2)}(2)] [R = Ph (), C(5)H(4)N-2 ()] and [PtTl(Cinsertion markN)(CN)(2)] [Cinsertion markN = bzq (), ppy ()], respectively. X-Ray diffraction studies of complexes show the existence of Pt(II)-Tl(I) bonds. In .CH(2)Cl(2) the platinum-thallium units are associated in tetranuclear Pt(2)Tl(2) entities which generate a 3-D network through short Tlpi(2-py) and pipi(bzq) contacts and additional weak Cl(2)HC-Hpi(C[triple bond, length as m-dash]C) nonclassical interactions. Compounds and show extended 2-D networks by connection of the organometallic "PtTl(Cinsertion markN)(CN)(2)" units, through secondary TlN[triple bond, length as m-dash]C contacts and moderate pipi(bzq) interactions in the case of . Complexes containing the bzq group exhibit in the solid state "luminescence thermochromism" associated to dual emission. At room temperature they show an intense, visible orange (: lambda(max) 625 nm), orange-red (: lambda(max) 640 nm) or yellow (: lambda(max) 582 nm) luminescence that changes to yellowish-green (: lambda(max) 532 nm) or green [: lambda(max) 524 nm; : lambda(max) 512 nm] upon cooling to 77 K. The unstructured low energy (LE) bands attributed to (3)pi-pi* excimeric emissions due to extensive pi-pi interactions are dominant at room temperature. By contrast, the high energy (HE) bands are highly structured and predominant at 77 K. Due to the presence of Pt-Tl bonds these HE emissions are bathochromically shifted in relation to the precursors' ones and have been tentatively assigned to a metal-metal'-to-ligand (bzq) charge transfer MM'LCT [d/s sigma*(Pt,Tl) -->pi*(Cinsertion markN)] mixed, as in the corresponding precursors, with some intraligand (3)IL[pi(Cinsertion markN') -->pi*(Cinsertion markN)] in and or ligand-to-ligand charge transfer (alkynyl to bzq) (3)LL'CT in complexes and . Complex [PtTl(ppy)(CN)(2)] , which does not show short contacts between the phenylpyridinate groups in solid state, only shows the HE green structured band both at 298 K and at 77 K. Only the cyanide derivatives are soluble and both spectroscopic (NMR and UV-Vis) and emission data (MeOH, 298 K and 77 K) indicate that the Pt(II)-Tl(I) bond breaks down in solution.

The pattern of expression of liver-specific and extrahepatic S-adenosylmethionine (SAM) synthetase in developing rat liver was established by determining steady-state levels of the respective messenger RNAs (mRNAs) and protein content. Levels of liver-specific SAM synthetase mRNA increased progressively from day 20 of gestation, increased 10-fold immediately after birth, and reached a peak at 10 days of age, decreasing slightly by adulthood. Conversely, mRNA levels of extrahepatic isoenzyme decreased toward birth, increased threefold in the newborn, and decreased further in the postnatal life, reaching a minimum in the adult. Similar expression profiles were observed in isolated hepatocytes, indicating that both mRNAs are differentially regulated in the same cell type. Western blot analysis showed that levels of immunoreactive liver-specific isoenzyme followed a trend similar to the mRNA, indicating that developmental regulation of this enzyme is mediated at the mRNA level. Developmental patterns of expression of albumin and alpha-fetoprotein (AFP) mRNAs were closely related to those for liver-specific and extrahepatic isoenzymes, respectively. Therefore, it is suggested that liver-specific SAM synthetase may be a marker for hepatocyte differentiation. Incubation of primary cultures of hepatocytes from 21-day-old fetuses with permeant cyclic adenosine monophosphate (cAMP) analogues elicited an up-regulation of the mRNA for the liver-specific isoenzyme with a concomitant down-regulation of the extrahepatic message, suggesting a physiological role for the increased postnatal glucagonemia in the control of this isoenzyme switching. In contrast with the isoenzyme expression profiles, the levels of SAM, the product of SAM synthetase reaction, were determined to be greater during gestation than in immediate postnatal periods. These results indicate that synthesis and utilization of SAM may be regulated differentially in fetal and adult hepatocytes.

Novel bimetallic neutral [(C6F5)4PtCd(cyclen)] and [(C6F5)2(C⋮CPh)2PtCd(cyclen)] (1, 2) and cationic [(C6F5)2(bzq)PtCd(cyclen)](ClO4) (3) pentafluorophenylplatinum(II)−cadmium(II) derivatives have been prepared by treatment of the adequate anionic starting precursors [Pt(C6F5)2X2] n - (n = 2, X = C6F5, C⋮CPh; n = 1, X2 = bzq) with Cd(ClO4)2 and cyclen. X-ray diffraction studies on complexes 1, 2, and 3 show that they are stabilized by a short Pt→Cd donor acceptor bond and, additionally, in complex 2 the Cd center is also coordinated to the Cα of one of the two alkynyl groups. In contrast, treatment of the binuclear compound [NBu4]2[Pt2(μ-Cl)2(C6F5)4] with [Cd(cyclen)(MeOH)2](ClO4)2 afforded the tetranuclear derivative [Pt(C6F5)2Cl(μ-Cl)Cd(cyclen)]2 (4) (X-ray), in which Pt and Cd atoms are connected by a μ3-Cl bridging ligand, and the binuclear cadmium complex [Cd2(μ-Cl)2(cyclen)2](ClO4)2 (5) (X-ray), in which two “Cd(cyclen)” fragments are bridged by two chlorine atoms. The photoluminescent properties of complexes 1−3 have also been examined and compared with those of their corresponding anionic parent compounds [NBu4]2[Pt(C6F5)4], [PMePh3]2[Pt(C6F5)2(C⋮CPh)2], and [NBu4][Pt(C6F5)2(bzq)] (6).

A novel series of [PtTl(2)(C[triple chemical bond]CR)(4)](n) (n = 2, R = 4-CH(3)C(6)H(4) (Tol) 1, 1-naphthyl (Np) 2; n = infinity, R = 4-CF(3)C(6)H(4) (Tol(F)) 3) complexes has been synthesized by neutralization reactions between the previously reported [Pt(C[triple chemical bond]CR)(4)](2-) (R = Tol, Tol(F)) or novel (NBu(4))(2)[Pt(C[triple chemical bond]CNp)(4)] platinum precursors and Tl(I) (TlNO(3) or TlPF(6)). The crystal structures of [Pt(2)Tl(4)(C[triple chemical bond]CTol)(8)]4 acetone, 14 acetone, [Pt(2)Tl(4)(C[triple chemical bond]CNp)(8)]3 acetone1/3 H(2)O, 23 acetone 1/3 H(2)O and [[PtTl(2)(C[triple chemical bond]CTol(F))(4)](acetone)S](infinity) (S = acetone 3 a; dioxane 3 b) have been solved by X-ray diffraction studies. Interestingly, whereas in the tolyl (1) and naphthyl (2) derivatives, the thallium centers exhibit a bonding preference for the electron-rich alkyne entities to yield crystal lattices based on sandwich hexanuclear [Pt(2)Tl(4)(C[triple chemical bond]CR)(8)] clusters (with additional Tlacetone (1) or Tlnaphthyl (2) secondary interactions), in the C(6)H(4)CF(3) (Tol(F)) derivatives 3 a and 3 b the basic Pt(II) center forms two unsupported Pt-Tl bonds. As a consequence 3 a and 3 b form an extended columnar structure based on trimetallic slipped PtTl(2)(C[triple chemical bond]CTol(F))(4) units that are connected through secondary Tl(eta(2)-acetylenic) interactions. The luminescent properties of these complexes, which in solution (blue; CH(2)Cl(2) 1,2; acetone 3) are very different to those in solid state (orange), have been studied. Curiously, solid-state emission from 1 is dependent on the presence of acetone (green) and its crystallinity. On the other hand, while a powder sample of 3 is pale yellow and displays blue (457 nm) and orange (611 nm) emissions, the corresponding pellets (KBr, solid) of 3, or the fine powder obtained by grinding, are orange and only exhibit a very intense orange emission (590 nm).

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,

The alkynylation of [Pt(bzq)(µ-Cl)] 2 (bzqH = benzo[h]quinoline) with excess of LiC᎐ ᎐ ᎐ CR in diethyl ether leads to novel (7,8-benzoquinolinate)bis(alkynyl)platinate() monoanionic species [Pt(bzq)which have been isolated as tetrabutylammoniun salts. The molecular X-ray structures of 3 and 6 reveal the presence of discrete anions with bond lengths and angles similar to those of related cyclometalated Pt compounds and no evidence of π-π or Pt-Pt stacking interactions. The influence of the R substituent on the photophysics of the complexes has been examined by UV-visible absorption, emission spectroscopy and cyclic voltammetry. Complexes 1-6 show a similar strong luminescence in both the solid state (structureless emission) and frozen solutions (well-resolved vibronic structures) while the emissions in solution at room temperature are red shifted (relative to the glass) and weak. For these complexes, on the basis of TD-DFT calculations which reproduce the experimental structure of anion 3, [Pt(bzq)(C᎐ ᎐ ᎐ CPh) 2 ] Ϫ , the emissions are proposed to arise from mixed [π C᎐ ᎐ ᎐ CR/Pt d/π (bzq) π* bzq] transitions. In contrast, complex 7 which contains the extended p-phenylethynylphenylacetylide ligand, C᎐ ᎐ ᎐ CC 6 H 4 -C᎐ ᎐ ᎐ CPh, displays a structured emission both at 298 K and in glassy CH 2 Cl 2 solutions. In this case the lack of a significant rigidochromism and DFT theoretical calculations support the involvement of a low-lying, metal perturbed acetylenic 3 ππ* (C᎐ ᎐ ᎐ CC 6 H 4 -C᎐ ᎐ ᎐ CPh) excited state.

A family of homoleptic tetraalkynylplatinate() complexes (NBu 4 ) 2 [Pt(C᎐ ᎐ ᎐ CR) 4 ] containing various arylsubstituted (R = C 6 H 4 X), where X is an electron-donating, -withdrawing or -delocalizing substituent, and ethynylpyridine (C 5 H 4 N-2, C 5 H 4 N-4) ligands have been prepared. The structures of complexes with R = (4-CF 3 )C 6 H 4 (4ؒ2HCCl 3 ), (4-CN)C 6 H 4 (6ؒH 2 O) and C 5 H 4 N-4 (9bؒHC᎐ ᎐ ᎐ CC 5 H 4 N-4ؒ2H 2 O) have been determined by single-crystal X-ray diffraction. While in the case of 4 two molecules of CHCl 3 are incorporated to the anion by short CH ؒ ؒ ؒ π interactions, for the para-pyridylethynyl derivative one H 2 O molecule connect different anions through moderate N ؒ ؒ ؒ H-O-H ؒ ؒ ؒ N intermolecular interactions, giving an extended one-dimensional chain. The photophysical and electrochemical properties of the complexes have been examined. All of them display emissions at 77 and 298 K in the fluid and solid state, with lifetimes in the microsecond regime. In some cases the emission profile is clearly the envelope of several closely bands, whose relative intensity depends on the excitation energy. On the basis of TD-DFT theoretical calculations on the anion [Pt{C᎐ ᎐ ᎐ C(4-CN)C 6 H 4 } 4 ] 2Ϫ of complex 6, it is proposed that the emissions are due to triplet intraligand excited states, with both an aryl (or pyridyl) and acetylenic character, which arise from an admixture of π π*(C᎐ ᎐ ᎐ CR) IL and d π (Pt) π*(C᎐ ᎐ ᎐ CR) MLCT transitions.

New alkynyl complexes [Pt2M4{CC(3-OMe)C6H4}8] (M = Ag 1, Cu 2) have been synthesized and their structures and properties compared to those of related [Pt2M4(CCPh)8] compounds. For the Pt-Ag derivatives, the X-ray structures of the discrete yellow solvate monomer, [Pt2Ag4{CC(3-OMe)C6H4}8].2THF ([1.2THF]), and the dark garnet unsolvated polymeric form, [Pt2Ag4{CC(3-OMe)C6H4}8](infinity) ([1](infinity)), are presented. The yellow form ([1.2THF]) exhibits a distorted octahedral geometry of the metal centers with the platinum atoms mutually trans and the four silver atoms in the equatorial plane. Pairs of Ag atoms are weakly bridged by THF molecules [mu-Ag2...O(THF)]. The garnet form ([1](infinity)) has an unprecedented infinite stacked chain of octahedral clusters linked by short Pt...Pt bonds (3.1458(8) A). In both forms, different types of weak C-H...O (OMe) hydrogen bonds are observed. For comparative purposes, we have also provided the crystal structures of the yellow monomer form, [Pt2Ag4-(CCPh)8].CHCl3, and the red dimer form, [Pt2Ag4(CCPh)8]2 (Pt-Pt 3.221(2) A). These clusters display intense photoluminescence in both solution and the solid state, at room temperature and 77 K. The emission observed for the yellow form [1.2THF] in the solid state is assigned to a 3MLM'CT [Pt(d)/pi(CCR) --> Pt(p(z))/Ag(sp)/pi(CCR)] state modified by Pt...Ag, Ag...Ag, and Ag...(THF) contacts. However, in the garnet form [1](infinity) and in 2, the emissions are related to the axial Pt-Pt bonds and are assigned as phosphorescence from a metal-metal-to-ligand charge-transfer (3MMLCT) excited state ([1](infinity)), or an admixture of a metal-metal (Pt-Pt) centered 3(dsigmap(z)sigma) and 3MMLCT excited state (2). For 1, a remarkable quenching and a shift to higher energies in the emission is observed on changing from CH2Cl2 to THF, and for both 1 and 2, the emission spectra at 77 K varies with the concentration, showing their tendency to stack even in glass.