Organogel of an 8-quinolinol platinum(II) chelate derivative and its efficient phosphorescence emission effected by inhibition of dioxygen quenching

A newly synthesized 8-quinolinol platinum(II) chelate derivative gelates various organic solvents, and the gel formed shows unique thermo- and solvatochromism of visible and phosphorescent colour in response to a sol-gel phase transition and possesses an attractive ability to inhibit dioxygen quenching of excited triplet states.     

DFT/TDDFT insight into the impact of ring size of the NHC chelating unit of high effective phosphorescent Platinum (II) complexes

Uncovering the photodeactivation mechanisms of unique N‐heterocyclic carbene (NHC)‐based transition metal complexes is favorable for designing more high‐efficiency phosphorescent materials. In this work, four bidentate platinum (II) complexes with NHC‐chelate are investigated by the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) to probe into how the ring size of NHC‐chelate unit influences on electronic structures and the phosphorescent properties. To illustrate the photodeactivation mechanisms clearly, three significant photodeactivation processes (radiative decay process, temperature‐independent and temperature‐dependent nonradiative decay processes) were taken into consideration. We stated that radiative decay rate constants k_r slightly increased with declined number of NHC‐chelate ring, owing to the gradually larger SOC matrix elements between the T₁ state and S_n states. Combining the temperature‐independent with temperature‐dependent nonradiative decay processes, the nonradiative decay rate k_nr is Pt‐4 (five‐membered) < Pt‐3 (six‐membered) < Pt‐2 (seven‐membered) < Pt‐1 (eight‐membered). The calculated results testify that the decrease of size of the NHC chelating unit is a reliable insurance to improve the quantum yield. The designed complex Pt‐4 with five‐membered NHC‐ring can serve as a highly efficient phosphorescent material in the future. The results indicated controlling the ring size of NHC‐chelate is a feasible method to tune phosphorescence properties of Pt (II) complexes.     

Origin of the Aggregation-Induced Phosphorescence of Platinum(II) Complexes: The Role of Metal–Metal Interactions on Emission Decay in the Crystalline State

Discerning the origins of the phosphorescent aggregation-induced emission (AIE) from Pt(II) complexes is crucial for developing the broader range of photo-functional materials. Over the past few decades, several mechanisms of phosphorescent AIE have been proposed, however, not have been directly elucidated. Herein, we describe phosphorescence and deactivation processes of four class of AIE active Pt(II) complexes in the crystalline state based on experimental and theoretical investigation. These complexes show metal-to-ligand and/or metal−metal-to-ligand charge transfer emission in crystalline state with different heat resistance against thermal emission quenching. The calculated energy profiles including the minimum energy crossing point between S₀ and T₁ states were consistent with the heat resistant properties, which provided the mechanism for AIE expression. Furthermore, we have clarified the role of metal-metal interaction in AIE by comparing two computational models.     

Bluish-Green BMes(2) -Functionalized Pt(II) Complexes for High Efficiency PhOLEDs: Impact of the BMes(2) Location on Emission Color

New phosphorescent Pt(II) compounds based on dimesitylboron (BMes(2) )-functionalized 2-phenylpyridyl (ppy) N,C-chelate ligands and an acetylacetonato ancillary ligand have been achieved. We have found that BMes(2) substitution at the 4'-position of the phenyl ring can blue-shift the phosphorescent emission energy of the Pt(II) compound by approximately 50?nm, compared to the 5'-BMes(2) substituted analogue, without substantial loss of luminescent quantum efficiencies. The emission color of the 4'-BMes(2) substituted Pt(II) compound, Pt(Bppy)(acac) (1) can be further tuned by the introduction of a substituent group at the 3'-position of the phenyl ring. A methyl substituent red-shifts the emission energy of 1 by approximately 10?nm whereas a fluoro substituent blue-shifts the emission energy by about 6?nm. Using this strategy, three bright blue-green phosphorescent Pt(II) compounds 1, 2 and 3 with emission energy at 481, 492, and 475?nm and Φ(PL) =0.43, 0.26 and 0.25, respectively, have been achieved. In addition, we have examined the impact of BMes(2) substitution on 3,5-dipyridylbenzene (dpb) N,C,N-chelate Pt(II) compounds by synthesizing compound 4, Pt(Bdpb)Cl, which has a BMes(2) group at the 4'-position of the benzene ring. Compound 4 has a phosphorescent emission band at 485?nm and Φ(PL) =0.70. Highly efficient blue-green electroluminescent (EL) devices with a double-layer structure and compounds 1, 3 or 4 as the phosphorescent dopant have been fabricated. At 100?cd?m(-2) luminance, EL devices based on 1, 3 and 4 with an external quantum efficiency of 4.7, 6.5 and 13.4?%, respectively, have been achieved.     

A Phosphorescent Molecular “Butterfly” that undergoes a Photoinduced Structural Change allowing Temperature Sensing and White Emission

A butterfly‐like phosphorescent platinum(II) binuclear complex can undergo a molecular structure change in which the Pt–Pt distance shortens upon photoexcitation, which leads to the formation of two distinct excited states and dual emission in the steady state, that is, greenish‐blue emission from the high‐energy excited state at the long Pt–Pt distance and red emission from the low‐energy excited state at the short Pt–Pt distance. This photoinduced molecular structure change has a strong dependence on the molecule’s surrounding environment, allowing its application as self‐referenced luminescent sensor for solid–liquid phase change, viscosity, and temperature, with greenish‐blue emission in solid matrix and rising red emission in molten liquid phase. With proper control of the surrounding media to manipulate the structural change and photophysical properties, a broad white emission can be achieved from this molecular butterfly.     

Reversibly reducible cis-dichloroplatinum(II) and cis-dichloropalladium(II) complexes of bis(1-methylimidazol-2-yl)glyoxal

Complexes cis-MCl2(big), big=bis(1-methylimidazol-2-yl)glyoxal, M=Pt, Pd, were prepared and characterized through electrochemistry, spectroscopy, and for M=Pt, by X-ray structure analysis. The seven-membered chelate ring formed through N,N' coordination of the ligand big shows a boat conformation in agreement with density functional theory (DFT) calculation results. No significant intermolecular interactions were observed for the platinum compound. Both the PdII and PtII complexes undergo reversible one-electron reduction in CH2Cl2/ 0.1 M Bu4NPF6; the reduced palladium compound disintegrates above -30 degrees C. Electron paramagnetic resonance (EPR), UV-vis, and IR spectroelectrochemistry studies were employed to study the monoanions. The anion radical complex [cis-PtCl2(big)]*- exhibits a well-resolved EPR spectrum with small but well-detectable g anisotropy and an isotropic 195Pt hyperfine coupling of 12.2 G. DFT calculations confirm the spin concentration in the alpha-semidione part of the radical complex with small delocalization to the bis(imidazolyl)metal section. The results show that EPR and electroactive moieties can be linked to the cis-dichloroplatinum(II) group via imidazole coordination.     

Synthesis and characterisation of transition metal halide complexes of the xylyl-distibine, 1,2-bis(dimethylstibanylmethyl)benzene

Complexes of the title ligand with Cu(I), Ag(I), Au(I), Pd(II), Pt(II), Rh(III), and rare examples with Ni(II) and Co(III) have been prepared and characterised by analysis, IR, UV-vis, 1H, 63Cu and 59Co NMR spectroscopy and ES+ mass spectrometry as appropriate. The structures of [Cu[1,2-C6H4(CH2SbMe2)2]2]BF4, [PtCl2[1,2-C6H4(CH2SbMe2)2]], [M[1,2-C6H4(CH2SbMe2)2]2][PF6]2 (M = Pd or Pt), and [NiI[1,2-C6H4(CH2SbMe2)2]2]ClO4 have been determined, and the varying chelate bite and conformations of the xylyl backbone in these structures are discussed. Despite the unfavourable seven-membered chelate ring and the large soft antimony donors, 1,2-C6H4(CH2SbMe2)2 proves to be a surprisingly good ligand for late transition metals in medium oxidation states.     

Metal-metal interactions in dinuclear d(8) metal cyanide complexes supported by phosphine ligands. Spectroscopic properties and ab initio calculations of [M(2)(mu-diphosphine)(2)(CN)(4)] and trans-[M(phosphine)(2)(CN)(2)] (M = Pt,Ni)

Structural, spectroscopic properties on the dinuclear [M(2)(dcpm)(2)(CN)(4)] (M = Pt, 1a; Ni, 2a, dcpm = bis(dicyclohexylphosphino)methane) and [M(2)(dmpm)(2)(CN)(4)] (M = Pt, 1b; Ni, 2b, dmpm = bis(dimethylphosphino)methane) and the mononuclear trans-[M(PCy(3))(2)(CN)(2)] (M = Pt, 3; Ni, 4, PCy(3) = tricyclohexylphosphine) and theoretical investigations on the corresponding model compounds are described. X-ray structural analyses reveal Pt.Pt and Ni.Ni distances of 3.0565(4)/3.189(1) A and 2.957(1)/3.209(8) A for 1a/1b and 2a/2b, respectively. The UV-vis absorption bands at 337 nm (epsilon 2.41 x 10(4) dm(3) mol(-)(1) cm(-)(1)) for 1a and 328 nm (epsilon 2.43 x 10(4) dm(3) mol(-)(1) cm(-)(1)) for 1b in CH(2)Cl(2) are assigned to (1)(5d(sigma) --> 6p(sigma)) electronic transitions originating from Pt(II)-Pt(II) interactions. Resonance Raman spectroscopy of 1a, in which all the Raman intensity appears in the Pt-Pt stretch fundamental (93 cm(-)(1)) and overtone bands, verifies this metal-metal interaction. Complexes 1a and 1b exhibit photoluminescence in the solid state and solution. For the dinuclear nickel(II) complexes 2a and 2b, neither spectroscopic data nor theoretical calculation suggests the presence of Ni(II)-Ni(II) interactions. The intense absorption bands at lambda > 320 nm in the UV-vis spectra of 2a and 2b are tentatively assigned to d --> d transitions.     

Effect of acidity on the extraction and kinetic stability of the copper(II)/APCD/IBMK system in strongly acidic media

The extraction of copper(II) from strongly acidic solution (0.01-8M hydrochloric acid) with ammonium 1-pyrrolidinecarbodithioate in isobutyl methyl ketone has been investigated. The shaking time needed for quantitative extraction decreases as the acidity is increased. The effect of the mutual solubility of the organic solvent and the aqueous phase is significant when the acidity of the aqueous phase is increased. The acidity of the aqueous phase mainly affects the kinetic stability of the chelate during the shaking period, rather than the decomposition of the chelating agent. The kinetic stability of the chelate apparently depends on the mole ratio of reagent to copper, the half-lives for the chelate extracted from 4M hydrochloric acid being 29.0, 40.0 and 85.0 min for reagent: metal mole ratios of 10, 100 and 1000, respectively.     

The effect of phenyl group on the electronic and phosphorescent properties of cyclometalated analogues of platinum(II) terpyridine complexes: a theoretical study

In this work, we theoretically investigate the effect of phenyl group on the electronic and phosphorescent properties of cyclometalated platinum(II) complexes, thereby designing an efficient blue emitting material. Three platinum(II) complexes Pt(N^N^N)Cl (N^N^N = terpyridine), Pt(N^C^N)Cl (N^C^N = 1,3-di(2-pyridyl)-benzene) and Pt(N^N^C)Cl (N^N^C = 6-phenyl-2,2′-bipyridines) are chosen as the models. Their electronic and phosphorescent properties are investigated utilizing quantum theoretical calculations. The results reveal that the phenyl group significantly affects the molecular and electronic structures, charge distribution and phosphorescent properties. The coordination bond length trans to phenyl group is the longest among the same type of bonds owing to the trans influence of phenyl group. Moreover, the phenyl group largely restricts the geometry relaxation of cyclometalated ligand. The strong σ-donor ability of Pt–C bond makes more electrons center at Pt atom and the fragments trans to phenyl group. In comparison with Pt(N^N^N)Cl and Pt(N^N^C)Cl, the complex Pt(N^C^N)Cl has the smallest excited-state geometry relaxation and the biggest emission energy and spatial overlap between the transition orbitals in the emission process. As a result, Pt(N^C^N)Cl has the largest emission efficiency, which well agrees with the experimental observation. Based on these calculation results, a potentially efficient blue-emitting material is designed via replacing pyridine groups in Pt(N^C^N)Cl by 3-methylimidazolin-2-ylidene.     

Luminescent organoplatinum(II) complexes with functionalized cyclometalated C^N^C ligands: structures, photophysical properties, and material applications

A series of [(R'-C^N^C-R')Pt(L)] complexes with doubly deprotonated cyclometalated R'-C^N^C-R' ligands (R'-C^N^C-R'=2,6-diphenylpyridine derivatives) functionalized with carbazole, fluorene, or thiophene unit(s) have been synthesized and their photophysical properties studied. The X-ray crystal structures reveal extensive intermolecular π···π and C-H···π interactions between the cyclometalated C^N^C ligands. Compared to previously reported cyclometalated platinum(II) complexes [(C^N^C)Pt(L)], which are non-emissive in solution at room temperature, the carbazole-, fluorene- and thiophene-functionalized [(R'-C^N^C-R')Pt(L)] (L=DMSO 1-9, C≡N-Ar, 1a-9a) complexes are emissive in solution at room temperature with λ(max) at 564-619 nm and Φ=0.02-0.26. The emissions of the [(R'-C^N^C-R')Pt(L)] complexes are attributed to electronic excited states with mixed (3)MLCT and (3)IL character. The carbazole/fluorene/thiophene unit(s) allow the tuning of the electronic properties of the [(R'-C^N^C-R')Pt] moiety, with the emission maxima in a range of 564-619 nm. These are the first examples of organoplatinum(II) complexes bearing doubly deprotonated cyclometalated C^N^C ligands that are emissive in solution at room temperature. In non-degassed DMSO, the emission intensities of 6a-9a are enhanced upon exposure to ambient light. This phenomenon is caused by reacting photogenerated (1)O(2) with a DMSO molecule to form dimethyl sulfone, leading to the removal of dissolved oxygen in solution. Self-assembled nanowires and nanorods are obtained from precipitation of 3a in THF/H(2)O and 8a in DMSO/Et(2)O, respectively. The [(R'-C^N^C-R')Pt(L)] complexes are soluble in common organic solvents with a high thermal stability (>300 °C), rendering them as phosphorescent dopants for organic light-emitting diode (OLEDs) applications. Red OLEDs with CIE coordinates of (0.65±0.01, 0.35±0.01) were fabricated from 7a or 8a. A maximum external efficiency (η(Ext)) of 12.6% was obtained for the device using 8a as emitter.     

High-efficiency red electrophosphorescence based on neutral bis(pyrrole)-diimine platinum(II) complex

Efficient red electroluminescence from the excimer or oligomer of neutral phosphorescent bis(pyrrole)-diimine Pt(II) complex has been achieved with maximum external quantum efficiency, luminous efficiency, power efficiency and brightness of 6.5%, 9.0 cd A(-1), 4.0 lm W(-1) and 11 100 cd m(-2), respectively.     

Determination of ciprofloxacin with a room-temperature phosphorescence flow-through sensor based on lanthanide-sensitized luminescence

Direct measurement of the sensitized luminescence of the europium-ciprofloxacin chelate immobilized on a cationic exchanger was used to develop a flow-through room-temperature phosphorescence optosensor for determination of ciprofloxacin. The phosphorescent chelate is formed on-line at room temperature in a flow-injection system and is immobilized on a weakly acidic cation-exchange resin packed in a flow cell. Optimum experimental conditions and analytical performance are discussed in detail. The sensor response for ciprofloxacin was linear, from 1.5 x 10(-6) to 2.0 x 10(-5)M with a relative standard deviation of 2.5% (n = 10) and a detection limit of 1.1 x 10(-7)M. The effect of possible interferences on sensor response was studied. The sensor was successfully tested for the determination of ciprofloxacin in pharmaceutical formulations.     

Light-emitting tridentate cyclometalated platinum(II) complexes containing sigma-alkynyl auxiliaries: tuning of photo- and electrophosphorescence

The synthesis and structural, photophysical, electrochemical, and electroluminescent properties of a class of platinum(II) complexes bearing sigma-alkynyl ancillary ligands, namely [(C/N/N)Pt(C[triple bond]C]nR] [H(C/N/N) = 6-aryl-2,2'-bipyridine; n = 1-4; R = aryl, alkyl, or trimethylsilyl], have been studied. Substituents with different steric and electronic properties were introduced into the tridentate cyclometalating and arylacetylide ligands, and the pi-conjugation length of the oligoynyl moiety was homologously extended from ethynyl to octatetraynyl. The X-ray crystal structures of several derivatives confirm the Pt-(CC) ligation and reveal various intermolecular interactions, such as pi-pi, Pt...Pt, and C-H...F-C. The complexes display good thermal stability and intense phosphorescence in fluid and glassy solutions with high quantum yields and microsecond lifetimes. Their emission energies are sensitive to solvent polarity, the electronic affinities of the substituents on both the cyclometalating and arylacetylide groups, and the length of the oligoynyl ligand. By choosing appropriate cyclometalating and sigma-alkynyl ligands, the emission color of this class of platinum(II) complexes can be tuned from green-yellow to saturated red. In addition to (3)MLCT [Pt(5d) --> pi*(C/N/N)] and (3)IL(C/N/N), intriguing (3)IL(alkynyl) excited states localized on -(C[triple bond]C)(4)- and -(C[triple bond]Cpyrenyl-1) moieties that afford narrow-bandwidth emissions have been observed. Selected Pt(II) complexes were doped into the emissive region of multilayer, vapor-deposited organic light-emitting diodes. The tunable electrophosphorescence energy resembles that recorded in fluid solutions for these emitters, and the devices exhibit high luminance and efficiencies (up to 4.2 cd A(-1)).     

A Phosphorescent Platinum(II) Bipyridyl Supramolecular Polymer Based on Quadruple Hydrogen Bonds

A platinum(II) bipyridyl complex bearing bis‐ureidopyrimidinone (Pt‐bisUPy) has been designed and its self‐assembling behavior has been thoroughly investigated by ¹H NMR, DOSY NMR, Ubbelohde viscometry analysis, UV/Vis, and emission spectroscopies. Pt‐bisUPy underwent concentration‐dependent ring‐chain polymerization in apolar solvents. Hydrogen‐bonding interactions play an important role during the formation of the supramolecular polymers. Hydrogen‐bonded supramolecular polymers were transformed to nanoparticles in water through the miniemulsion method. These nanoparticles showed strong π–π excimeric emission. Metal‐metal‐to‐ligand charge transfer (MMLCT) from Pt–Pt interactions was not significant in the emission spectrum. The phosphorescence of the nanoparticle persisted even under aerobic conditions. The triplet state of these phosphorescent nanomaterials were long‐lived and possessed moderate emission quantum yields. Furthermore, the low toxicity of these materials promises a place for them in in vitro and in vivo bioimaging.     

Synthesis, photophysical and electrophosphorescent properties of fluorene-based platinum(II) complexes

A series of platinum(II) complexes bearing tridentate cyclometalated C^N^N (C^N^N=6-phenyl-2,2'-bipyridine and π-extended R-C^N^N=3-[6'-(naphthalen-2'-yl)pyridin-2'-yl]isoquinoline) ligands with fluorene units have been synthesised and their photophysical properties have been studied. The fluorene units are incorporated into the cyclometalated ligands by a Suzuki coupling reaction. An increase in the π-conjugation of the cyclometalated ligands confers favourable photophysical properties compared to the 6-phenyl-2,2'-bipyridine analogues. The fluorene-based platinum(II) complexes display vibronic-structured emission bands with λ(max)=558-601 nm, and high emission quantum yields up to 0.76 in degassed dichloromethane. Their emissions are tentatively assigned to excited states with mixed (3)IL/(3)MLCT parentage (IL=intraligand, MLCT=metal-to-ligand charge transfer). The crystal structures of these platinum(II) complexes reveal extensive Pt(II)···π and/or π-π interactions. The fluorene-based platinum(II) complexes are soluble in organic solvents, have high thermal stability with decomposition temperature >350 °C, and can be thermally vacuum-sublimed or solution-processed as phosphorescent dopants for the fabrication of organic light-emitting diodes (OLEDs). A monochromic OLED with 3d as dopant (2 wt%) fabricated by vacuum deposition gave a current efficiency of 14.7 cd A(-1) and maximum brightness of 27000 cd m(-2). A high current efficiency (9.2 cd A(-1)) has been achieved in a solution-processed OLED using complex 3f (5 wt%) doped in a PVK (poly(9-vinylcarbazole)) host.     

Quantum dot nanocrystals having guanosine imprinted nanoshell for DNA recognition

Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP nanoparticles have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to CdS quantum dots (QDs), reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for DNA recognition. In this method, methacryloylamidohistidine-platinium (MAH-Pt(II)) is used as a new metal-chelating monomer via metal coordination-chelation interactions and guanosine templates of DNA. Nanoshell sensors with guanosine templates give a cavity that is selective for guanosine and its analogues. The guanosine can simultaneously chelate to Pt(II) metal ion and fit into the shape-selective cavity. Thus, the interaction between Pt(II) ion and free coordination spheres has an effect on the binding ability of the CdS QD nanosensor. The binding affinity of the guanosine imprinted nanocrystals has investigated by using the Langmuir and Scatchard methods, and experiments have shown the shape-selective cavity formation with O6 and N7 of a guanosine nucleotide (K(a) = 4.841x10(6) mol L(-1)) and a free guanine base (K(a) = 0.894x10(6) mol L(-1)). Additionally, the guanosine template of the nanocrystals is more favored for single stranded DNA compared to double stranded DNA.     

Synthesis,physico-chemical characterization and bioevaluation of Ni(II), Pd(II), and Pt(II) complexes with 1-(o-tolyl)biguanide: Antimicrobial and antitumor studies

New complexes of type [M(tbg)₂]Cl₂ [tbg = 1-(o-tolyl)biguanide; M = Ni(II), Pd(II), and Pt(II)] were synthesized and characterized to develop new biologically active compounds. The features of the complexes were assigned from microanalytical and thermal data. The NMR, FT-IR, and UV-Vis spectra were established by comparison with HtbgCl. All complexes exhibit a square-planar geometry resulting from the chelating behavior of tbg. The HtbgCl and [Ni(tbg)₂]Cl₂ complexes were fully characterized by single-crystal X-ray diffraction. The HtbgCl species crystallize in the monoclinic C2/c spatial group, while the Ni(II) complex adopts an orthorhombic Pna2₁ spatial group. The structure is stabilized by a complex hydrogen bonds network. The in vitro antimicrobial assays revealed improved antimicrobial activity for complexes in comparison with the ligand against both planktonic and biofilm embedded microbial cells. The most efficient compound, showing the largest spectrum of antimicrobial activity, including Gram-positive and Gram-negative bacteria, as well as fungal strains, in both planktonic and biofilm growth states was the Pd(II) complex, followed by the Pt(II) complex. The Pt(II) compound exhibited the most significant antiproliferative activity on the human cervical cancer SiHa cell line, inducing a cell cycle arrest in the G2/M phase.     

Quantum chemical study of redox-switchable second-order nonlinear optical responses of D-π-A system BNbpy and metal Pt(II) chelate complex

A second-order nonlinear optical (NLO) molecular switching with redox has been investigated in the present paper. The static first hyperpolarizabilities of 5-(BMes(2))-5'-(NPh(2))-2,2'-bipyridine (BNbpy) containing three-coordinate organoboron, Pt(II) chelate complex Pt(BNbpy)Ph(2), and their reduced forms have been calculated by density functional theory (DFT) combined with the analytic derivatives method. There is an enhancement of static first hyperpolarizabilities in the reduced form according to the calculations. That is, the β(vec) value of one-electron-reduced form is ~7 times as large as that of neutral form BNbpy; the β(vec) values of one- and two-electron-reduced forms are ~3 and ~4 times as large as that of neutral form Pt(BNbpy)Ph(2), respectively. In particular, the β(vec) value of two-electron-reduced form (3)Pt(BNbpy)Ph(2)(2-) is 1349 × 10(-30) esu, ~286 times larger than its neutral form. Moreover, the component β(z) value of the metal chelate complex Pt(BNbpy)Ph(2) is 25 × 10(-30) esu, which is ~14 times as large as that of ligand BNbpy; the corresponding F(-)/CN(-) compounds show a decrease in β(x) values compared with the case of the ligand and Pt(II) complex. Analyses of geometries, density of states (DOS), and time-dependent DFT (TDDFT) calculations reveal that the one-electron reduction promotes the molecular conjugation in the x-axis and intensifies the interaction between the metal Pt(II) and ligand and then results in an enhancement of the static first hyperpolarizability, whereas the binding of F(-)/CN(-) to the B atom turns off the p(π)-π* conjugation and has no effect on the conjugation of bipyridine, which leads to a decreasing β value in the x-axis.     

Solvent extraction and spectrophotometric determination of palladium(II) with 7-iodo-8-hydroxyquinoline-5-sulphonic acid

An extractive spectrophotometric procedure has been developed for the determination of palladium (II) at microgram levels. The palladium(II) chelate of 7-iodo-8-hydroxyquinoline-5-sulphonic acid is extracted into n-butanol. Extraction is maximal (95%) from 0.2M perchloric acid. Beer's law is valid at 430 nm over a wide range of palladium concentration from 2.5 ppm. The molar absorptivity is 958 1.mole(-1).mm(-1). The system can tolerate a large excess of Co(II), Ni(II), Rh(III), Pt(IV), Cr(III), W(VI), chloride, phosphate, citrate and tartrate. Small quantities of Ru(III), IR(III) and EDTA do not interfere, but serious interference is caused by Fe(III), V(V), Mo(VI) and Os(VIII).