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Synthesis and Investigation of Spectroscopic Properties and Excited State Electron Transfer Reactions of Pt(II) NCN Type Complexes

机译:Pt(II)NCN型配合物的光谱性质和激发态电子转移反应的合成与研究

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摘要

The world energy needs are always increasing, and an over-intensive use of fossil fuels has caused deleterious problems such as global warming. Maximum efforts need to be put in studying the ways to harness energy from clean renewable energy resources. Platinum NCN complexes are known to possess very high emission quantum yields with very high triplet lifetimes in the range of 2-6 micros in deaerated organic solvents. Most of the studies pertaining to the photochemistry of Platinum NCN molecules have been done in the field of OLEDs. The goal of this research was to study their excited state electron transfer reactions. The focus of this dissertation is 3 fold: (1) Synthesis of 1,3-dipyridylbenzene (NCN) ligands. (2) Synthesis of platinum(II) NCN complexes and study of their spectroscopic and electrochemical properties. (3) Investigation of photoinduced electron transfer reactions of Platinum NCN complexes.;The first chapter is an introduction to the past and the current energy scenario. World energy needs, consumption and availability is discussed. Further, the role of fossil fuels as a primary energy source, their effects on nature and the importance of the use of renewable energy sources such as solar energy is discussed. This leads to the discussion of the basics of photochemistry and the applications of some of the principles will be discussed as necessary in the following chapters.;Chapter 2 focuses on the Platinum complex chemistry and the syntheses of bispyridylbenzene ligands and the Platinum NCN complexes. In the introduction, properties of the platinum metal center are discussed. Square planar complexes of platinum with different type of bidentate and tridentate ligands are shown and their photophysical properties are compared. The axial interactions of some of the square planar platinumcomplexes are also discussed. Further, Platinum NCN complex chemistry is discussed in detail, highlighting the awesome photophysical properties of these type of complexes. This is followed by a detailed discussion of the synthesis of the NCN ligands using a [3+3]-type condensation reaction of O-acetyl oximes and alpha,beta-unsaturated aldehydes through synergistic and the platinum complexes. Pure ligands were synthesized in good yields and were characterized extensively using various NMR methods. The platinum complexes were synthesized and characterized by NMR and mass spectrometry. Crystal structures of 2 platinum complexes were obtained.;First half of chapter 3 focuses on the spectroscopic and electrochemical properties of the synthesized Platinum NCN complexes. The studies involved measurement of spectroscopic properties, redox potentials and spectroelectrochemical studies of the platinum complexes. All the complexes are intensely luminescent with emission quantum yields ranging from 10 -60%,, and triplet emission lifetimes ranging from 1-6 micros in deaerated chloroform and 200 ns - 20 micros in de-aerated N,N'-Dimethylformamide (DMF). All the complexes display 2 reversible reductions between -1.5 to -2 V vs Ag/AgCl. Electroanalytical investigations of the oxidation of square planar Pt(II) complexes, including NCN complexes, generally exhibit chemical irreversibility unless one or more coordinated ligands have reversible one electron oxidation. This leads to the discussion of the next part of chapter 3 which is determination of 1 electron oxidation potentials of these platinum NCN complexes on a faster time-scale using the Rehm - Weller approach. Oxidation potentials of PtPhNCNCl (PhNCN = 1,3-di(4-phenyl-2-pyridyl)benzene) and PtDMAPhNCNCl (DMAPh=1,3-di(4-(4-dimethylamino)phenyl-2 pyridyl)benzene) were determined using this approach. Using methyl viologen as a quencher, transient absorptionexperiments were done on PtPhNCNCl and PtDMAPhNCNCl which facilitated determination of the 1 electron oxidized spectra of these complexes.;It was found out that the PtPhNCNCl complex generates hydrogen if photolyzed in the presence of a reductive quencher and water. Chapter 4 involves hydrogen generation studies by photolyzing PtPhNCNCl complex in presence of triethylamine as the electron donating quencher and water as the proton donor in DMF. Photolysis was performed using 3 light sources: A PTI spectrofluorometer, and home-built Blue and UV LED cylinders. The PtPhNCNCl acts as a catalyst and a chromophore and, as such, it is a single component chromophore-catalyst system. After 2 hours of photolysis on the blue LED photoreactor with a photon flux of 4.4*10 18 quanta/min, the turnover number is 22 per mole of catalyst and 45 mmoles of hydrogen were generated with a quantum yield of 4.6 %. (Abstract shortened by ProQuest.).
机译:世界能源需求一直在增加,而过度使用化石燃料已引起诸如全球变暖等有害问题。需要尽最大的努力来研究利用清洁可再生能源中的能源的方法。已知NCN铂络合物在脱气的有机溶剂中具有很高的发射量子产率,并具有非常长的三重态寿命,范围为2-6微米。与铂NCN分子的光化学有关的大多数研究已在OLED领域进行。这项研究的目的是研究它们的激发态电子转移反应。本文的研究重点是三方面:(1)1,3-二吡啶基苯(NCN)配体的合成。 (2)NCN铂(II)配合物的合成及其光谱和电化学性质的研究。 (3)铂NCN配合物的光诱导电子转移反应的研究。第一章是对过去和当前能源情景的介绍。讨论了世界能源需求,消耗和可用性。此外,讨论了化石燃料作为主要能源的作用,其对自然的影响以及使用可再生能源如太阳能的重要性。这导致了对光化学基础知识的讨论,并将在以下各章中必要地讨论一些原理的应用。第二章着重于铂配合物化学以及双吡啶基苯配体和铂NCN配合物的合成。在介绍中,讨论了铂金属中心的性能。显示了具有不同类型的二齿和三齿配体的铂的方形平面复合物,并比较了它们的光物理性质。还讨论了一些方形平面铂络合物的轴向相互作用。此外,将对铂NCN配合物的化学性质进行详细讨论,以突出这些配合物的令人敬畏的光物理性质。接下来是使用O-乙酰肟和α,β-不饱和醛通过协同和铂配合物的[3 + 3]型缩合反应合成NCN配体的详细讨论。以高收率合成纯的配体,并使用各种NMR方法对其进行广泛表征。合成了铂配合物,并通过NMR和质谱表征。得到了两种铂配合物的晶体结构。第三章的上半部分着眼于合成的铂NCN配合物的光谱和电化学性质。这些研究涉及光谱性质,氧化还原电势的测量以及铂配合物的光谱电化学研究。所有配合物均发出强烈的光,发射量子产率为10 -60%,在脱气的氯仿中三线态发射寿命为1-6微米,在脱气的N,N'-二甲基甲酰胺(DMF)中为200 ns-20微米。 。与Ag / AgCl相比,所有复合物在-1.5至-2 V之间均显示2个可逆还原。方形平面Pt(II)配合物(包括NCN配合物)氧化的电分析研究通常显示出化学不可逆性,除非一种或多种配位体具有可逆的一个电子氧化。这导致对第3章下一部分的讨论,即使用Rehm-Weller方法在更快的时间范围内确定这些铂NCN络合物的1电子氧化电位。测定PtPhNCNCl(PhNCN = 1,3-二(4-苯基-2-吡啶基)苯)和PtDMAPhNCNCl(DMAPh = 1,3-二(4-(4-二甲基氨基)苯基-2吡啶基)苯的氧化电位使用这种方法。使用甲基紫精作为猝灭剂,在PtPhNCNCl和PtDMAPhNCNCl上进行了瞬态吸收实验,这有助于测定这些配合物的1电子氧化光谱;发现在还原性猝灭剂和水存在下光解时,PtPhNCNCl配合物会产生氢。 。第4章涉及在三乙胺作为给电子猝灭剂,水作为质子给体在DMF中的存在下,通过光解PtPhNCNCl络合物来制氢的研究。使用3种光源进行光解:PTI荧光分光光度计以及自制的蓝色和紫外线LED圆柱体。 PtPhNCNCl用作催化剂和生色团,因此,它是单组分生色团-催化剂体系。在蓝色LED光反应器上以4.4 * 10 18量子/分钟的光子通量进行2小时的光解后,周转数为22 /摩尔催化剂,产生45毫摩尔的氢,量子产率为4.6%。 (摘要由ProQuest缩短。)。

著录项

  • 作者

    Kulkarni, Aditya.;

  • 作者单位

    Tulane University School of Science and Engineering.;

  • 授予单位 Tulane University School of Science and Engineering.;
  • 学科 Inorganic chemistry.
  • 学位 Ph.D.
  • 年度 2018
  • 页码 282 p.
  • 总页数 282
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 物理化学(理论化学)、化学物理学;
  • 关键词

  • 入库时间 2022-08-17 11:53:12

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