Emerging application of inorganic and organic

Pincer catalyst

1. Emerging Applications of Inorganic and Organic Materials in Sustainable Catalysis and Optoelectronics Dr. V. MADHU, M.Sc., Ph.D. Associate Professor Department of Applied Chemistry Karunya Institute of Technology and Sciences (Deemed to be University) Coimbatore - 641 114 E-mail: [email protected]

2. Catalysis Medicinal Chemistry Sustainable Chemistry Carbon Dioxide Conversion Water Splitting Batteries Solar Cells Food Chemistry Opto-electronics/Thermo-electric materials Surfaces and Interfaces Chemistry of Materials Environmental chemistry High energy materials Forensic Science Current Important Research Topics in Chemistry Catal . Sci . Technol . , 2014, 4, 2180-2181

3. Sustainable Catalysis Thermochromic Materials Materials For Optoelectronic Applications

4. Catalyst is a substance that increases the rate of the reaction at which a chemical system approaches equilibrium Catalyst?

5. Catalysis Role in Green Chemistry

6. Sustainable Catalysis To use earth-abundant metal catalysts Catalytic process for CO 2  conversion Energy‐efficient reactions Atom economy High selectivity Development catalyst based on green chemistry principle Catal . Sci . Technol . , 2014,4, 2235-2240 Green Chem., 2017, 19, 3707–3728

7. Borrowing Hydrogen Methodology Borrowing Hydrogen methodology (Hydrogen Auto Transfer Process) Activation of C-C, C-O and C-N bonds Atom-economical method Environmentally benign synthetic method The activation of 1° and 2° alcohols and amines Avoiding the direct use of molecular hydrogen Chem. Rev. 2018, 118, 4, 1410-1459 Chem. Rev. 2019, 119, 4, 2524-2549

8. ACS Catal.  2016, 6, 4184–4188 J. Am. Chem. Soc.  2016, 138, 10786–10789 ACS Catal . 2018, 8, 8525-8530 J. Org. Chem. 2019, 84, 3715-3724 ACS Catal . 2018, 8, 10300-10305 Catalysis Based on Borrowing Hydrogen C-N, C-C, C-O bond formation Precious metals like Ru, Rh, Ir used Phosphine based ligands Limited report on precious metal catalyst with Non-phosphine ligands

9. For good catalytic activity in cross-coupling reactions, phosphines typically need to be both basic (electron-rich) and sufficiently sterically encumbered (as defined by a cone angle of the substituents around the phosphorus atom) However, phosphines also have some drawbacks, notably many phosphines that are used in highly active catalysts are also highly reactive in their own right, particularly with respect to oxidation, and therefore require handling under inert atmospheres. PH3 itself and many trialkylphosphines (such as PMe3 and Pt Bu3) are highly flammable and (like elemental white phosphorus itself) often reported as pyrophoric. Hence, they must be handled with extreme care, released in situ from their phosphonium salts, or the metal–phosphine complexes used directly

10. Pincer ligands, that is, tridentate ligands that enforce meridional geometry upon complexation to transition metals Transition-metal complexes of pincer ligands provide exceptional stability have found important applications in synthesis, bond activation and catalysis. Pincer ligands Based Transition-metal complexes

11. Transition-metal complexes of electron-rich pincer ligands have found important applications in bond activation and catalysis Electron-rich pincer ligands can stabilize coordinatively unsaturated complexes Pincer ligands cooperate with the metal center in a synergistic manner leads unusual catalytic processes (Metal-ligand cooperation). Undergo bond-breaking and making processes through aromatization and de-aromatization of the pincer ligands. The de-aromatized complexes can then activate a chemical bond (H–Y, Y=H, OH, OR, NH 2 , NR 2 , C) by cooperation between the metal and the ligand. The overall process does not involve a change in the metal’s oxidation state

12. David Milstein, Chem. Rev., 2014,  114  , 12024–12087

13. The majority of efficient homogeneous catalytic (transfer) hydrogenation reactions proceeded using the precious metals and phosphine ligands Common drawbacks of phosphine ligands- Trivial methods, multi-step syntheses, handling under an inert atmosphere, expensive, thus potentially challenging to make on a large scale. The major goals for sustainable catalysis The replacement of expensive precious metals by cheap, low-toxic, and abundant base metals with similar or better reactivity. Bench-stable Phosphine-free ligand based first row transition metal-pincer complexes

14. Phosphorous free Air stable Gram scale synthesis Paramagnetic nature Distorted octahedral geometry NNN-nickel(II) Pincer Complex Catalyzed α -Alkylation of Unactivated Amides and Esters with Alcohols Via Borrowing Hydrogen process ChemSusChem 2018, 11, 3911 – 3916

15. Optimization Conditions Screening of catalyst α -Alkylation of Unactivated Amides and Esters with Alcohols ChemSusChem 2018, 11, 3911 – 3916

16. Screening of Solvent Reactions were performed using amide 3a (0.25 mmol), 4-Methyl benzyl alcohol 4c (0.125 mmol), catalyst 1 (2.5 mol%), KOtBu (1.1 equiv.) using 1 mL of solvent at 100oC. bYield determined by GC using 1,4-dibromo butane as an internal standard. NR = No reaction. Screening of Temperature

17. Screening of Base Screening of Catalyst Amount Screening of Amide Amount Screening of Base Amount

18. The scope of amines and alcohols for the alkylation of amides Reactions were performed using amide 3a (0.25 mmol), 4-Methyl benzyl alcohol 4c (0.125 mmol), catalyst 1 (2.5 mol%), KOtBu (1.1 equiv.) using 1 mL of solvent at 100oC. bYield determined by GC using 1,4-dibromo butane as an internal standard. NR = No reaction.

19. The scope of alcohols for the alkylation of esters ChemSusChem 2018, 11, 3911 – 3916

20. Mechanistic Investigation

21. Catalyst Recyclability Experiment ChemSusChem 2018, 11, 3911 – 3916

22. Preparation of Esters, amides, amines, acetals, and peptides- Challenges David Milstein , Angew. Chem. Int. Ed. 2010, 49, 1468-1471

23. Catal. Sci. Technol., 2018 , 8, 3469–3473 Direct Access to N -Alkylated Amines via Acceptorless Dehydrogenative Coupling and Borrowing hydrogen Catalyzed by Cobalt(II)-NNN Pincer Complex

24. Acceptorless Dehydrogenation Coupling Borrowing hydrogen (BH) The reaction operates under mild conditions with the liberation of dihydrogen and water as the by-products.

25. Alkylation of m -toluidine with various alcohols based on BH statergy

26. Alkylation of m-toluidine with various alcohols

27. Alkylation of various anilines with benzyl alcohols

28. Dehydrogenative coupling of various amines with alcohols

29. Application

30. Cobalt Complex Catalyzed Z-selective semi-hydrogenation of alkynes Chem. Commun. , 2017,53, 4612-4615  NH 3 BH 3

31. Hydrogenation Reactions Catalysed by Cobalt Complexes J. Am. Chem. Soc. , 2015,  137 , 7998–8001 Angew. Chem. Int. Ed. 2013, 52 , 14162 –14166

32. UV spectra of I, II and III d–d transition NNN-cobalt(II) pincer complex catalyzed Z -selective semi-hydrogenation of unbiased alkynes

33. Optimization of the Reaction Conditions a Reaction conditions: 1a (0.5 mmol), reductant (0.6 mmol), and cat.[Co] (4 mol%) in 1 mL of solvent at 50 o C for 12 h. b Conversion and yields were determined by GC analysis. c 20 mol% of NaBEt 3 H was used. d I n the presence of mercury . e 1:1 mixture.

34. Z -selective Semi-Hydrogenation of Alkynes These reactions operate under mild, neutral, phosphine ligand-free, additive and/or base-free conditions, as well as without the need of any special high-pressure equipment .

35. Scope of Terminal Alkynes

36. Cobalt-catalyzed Hydrogenation of Terminal Alkenes

37. Purification of Alkenes from Alkyne Impurities This unified process is highly stereo-, and chemo-selective Exhibits a broad scope (aliphatic, aromatic and chiral alkynes) as well as wide functional group tolerance, such as halides, alcohol, acetal, amine, ether, nitrile, nitro, ester and heterocyclic motif. This convenient protocal was successfuly applied into the selective removal of alkyne impurities from alkenes.

38. Mechanistic Studies

39. A plausible catalytic cycle

40. Earth-abundant, economical, benign cobalt-based phosphine-ligand free catalysts

41. Manganese(II)-NNN pincer complex catalyzed C-alkylation of cyclic amides with secondary alcohols Organometallics 2021, 40, 627−634

42. Optimization of the reaction conditions. a a Reaction conditions: 1a (0.5 mmol), 2a (1.0 mmol), Mn-catalyst (0.01 mmol), t - BuOK (0.60 mmol) and toluene (1.5 mL) were heated at 110 o C for 8 h under an argon atm. b Isolated yields. n.r . = no reaction.

43. Mn-catalyzed C-alkylation of oxindoles: Scope of secondary alcohols. a a Reaction conditions: 1a (0.5 mmol), 2 (1.0 mmol), Mn-catalyst I (or) II (0.01 mmol), t - BuOK (0.60 mmol), and toluene (1.5 mL) were heated at 110 o C for 8-10 h under argon atm. b Isolated yield with two isomer ratio. c For 14 h. d Dehydrogenated product fluorenone (75%) was observed. Organometallics 2021, 40, 627−634

44. Mn-catalyzed C-alkylation of oxindoles: Scope of oxindoles

45. A plausible mechanism Organometallics 2021, 40, 627−634

46. Application of Thermochromic Materials Coatings for smart buildings Defence applications Textiles Thermometers (Temperature sensor) Medical Bioimaging Displays Optical information recording Security applications Adv. Optical Mater. 2020, 1901687 Thermochromic Materials

47. Matter, 2019, 1, 1–12, Rewritable and Multi-level Security Printing

48. Coatings for smart buildings Textiles

49. Thermochromism of Nickel(II) Complex and SCSC Transformation Thermochromic Behavior and SCSC Transformation of 1 The DSC of complex 1 ACS Omega 2019, 4, 13756−13761

50. Solid state UV-Vis absorption spectra of 1 and 1B. Simulated UV-Vis absorption spectra of complexes 1 and 1B UV-Vis Absorption Spectral Studies

51. Structure and single crystal digital image of 1, 1B, 1C and 1D showing the existence of side arms in different conformation in ‘ cb ’ plane of crystals ACS Omega 2019, 4, 13756−13761

52. Supramolecular Dimeric Structure of Crystals of 1-1D Along Different Direction of Crystallographic Axis ACS Omega 2019, 4, 13756−13761

53. Photographs of reversible thermochromic behavior for complex 1-4 Temperature dependent PXRD patterns of 1 ACS Omega 2019, 4, 13756−13761

54. EPR Spectrum of 1(blue) and 1B(red)

55. Temperature Dependence of the Raman Spectra of Complex 1

56. 57 Optoelectronic Device Applications

57. 58 Light Emitting Diodes (LEDs) It is a Diode, which emits light when a suitable voltage is applied to the leads (p–n junction diode), electrons are able to recombine with electron holes within the device, releasing of photons. Type of Optoelectronic Devices J. Mater. Chem. C , 2017,5, 4763-4774 Photovoltaic Devices: It generates electricity by using light. When light reaches the p-n junction, thereby create a number of electron-hole pairs. The potential difference across the junction generates the current.

58. OLED Architectures Chem. Mater., 2001, 16, 4556 J. Mater. Chem. C, 2019,7, 7144-7158

59. 60 Basic Design Principle of LED devices The molecule with donor and acceptor combined structure. Donors and acceptors can be integrated in several different ways to adjust the photophysical properties that are key factors of the light-emitting performances of the optoelectronic devices. Donor and acceptor based structures (donor–acceptor) Donor– π linker–acceptor Donor– acceptor–donor, Donor–π linker–acceptor–π linker–donor, Donor– σ– acceptor Adv. Optical Mater. 2018 , 1800255

60. Thermally activated delayed fluorescent (TADF) materials have been known to achieve 100% theoretical internal quantum efficiency (IQE) by harvesting both singlet and triplet excitons through the efficient reverse intersystem crossing (RISC) process and are rapidly emerging as a substitute for phosphorescent organic light-emitting diodes Thermally activated delayed fluorescent (TADF)-OLED

61. 62 Donor– π linker–Acceptor J. Mater. Chem. C , 2017,5, 9828-9837 Dyes and Pigments, 2016, 134, 83-90

62. 63 RSC Adv. , 2015,5, 89171-89187 Donor– Acceptor–Donor

63. 64 Near-Infrared Emitting Iridium(III) complexes- Organic Light-emitting Diodes (OLEDs Adv. Optical Mater. 2020, 2000154

64. 65 Near-Infrared Luminescence Angew. Chem. Int. Ed., 2020, DOI: 10.1002/anie.202006197

65. 66 ACS Appl. Mater. Interfaces  2020

66. 67 Near-Infrared Ratiometric Organic Fluorescent Thermometer for Intracellular Temperature Sensing Wenjing Tian, ACS Applied Materials & Interfaces   2020, 12, 24, 26842-26851

67. 68 ACS Nano   2020, 14, 7, 8716-8723  Wearable and Semitransparent Pressure-Sensitive Light-Emitting   Sensor  

68. 69 Multiple Application of UV-Vis-NIR

69. Molecular Self-assembly and Optical Properties 95% yield. 70 Chemistry Select 2020, 5 , 2070 –2074

70. 1D Columnar Stack 71

71. The Influence of Reaction Temperature on the Crystallization, Absorption and Fluorescence Properties of PDIs The extended aromatic cycle stacking in the solid-state lead to red-shifted absorption due to the formation of Frenkel -CT mixing state. 72 Chemistry Select 2020, 5 , 2070 –2074

72. Mechanofluorochromism, polymer matrix controlled fluorescence tuning and structure-fluorescence properties of imidazole fused tetraphenylethylene AIEgens PMMA PVA thin films CrystEngComm, 2021, 23, 5403–5410

73. Fluorescence Switching Properties of 2,2'-Bipyridine Based Donor-Acceptor Derivatives New J. Chem. , 2020, 44, 14421--14428

74. Acceptorless Dehydrogenative Coupling and Borrowing hydrogen type of catalytic reaction based on cobalt, Nickel, and Manganese NNN Pincer Complex The catalytic reactions proceed under mild conditions, phosphine ligand-free conditions Reversible thermochromic behavior NNN-Ni(II) pincer complex Organic Materials for Optoelectronic materials Summary

75. Collaborators Research Group Members 1. Dr. J. Pitchaimani (Alumni) Mr. P. Nagarasu Ms. M. J. Tamilpriyai Mr. Jerome Issac Ms. Deepanjaly.K.S Financial Support Acknowledgement Dr. S. Philip Antony, SASTRA Deemed University Dr. Dohyun Moon , Pohang Accelerator Laboratory, Korea Dr. Ekambaram Balaraman, IISER Tirupati Adhiyamaan College of Engineering, 03.08.2021 KITS KAHEARC- 2021

76. THANK YOU