About

Janet Bluemel is a professor at Texas A&M University College of Arts and Sciences, specializing in chemistry with a focus on catalysis, surface chemistry of oxide materials, and solid-state NMR spectroscopy. Her research group investigates immobilized catalysts, which combine the advantages of heterogeneous and homogeneous catalysts, emphasizing their recyclability, activity, and selectivity. She explores heterobimetallic systems, such as the Sonogashira Pd/Cu catalyst, and studies the surface chemistry of oxide supports, including the reactivity and mobility of metal complexes and linkers on surfaces. Her work leverages solid-state NMR spectroscopy, optimized for surface-bound species, to analyze reactions on surfaces and characterize anchored catalysts and linkers. Bluemel's multidisciplinary approach spans synthetic chemistry, materials science, catalysis, and surface analytical methods, fostering industrial collaborations and contacts.

Research topics

• Organic chemistry
• Chemistry
• Chemical engineering
• Combinatorial chemistry
• Nuclear magnetic resonance
• Polymer chemistry

Selected publications

• TEMPO in Solution, Melted, Solid, and Adsorbed on a Silica Surface: A Paramagnetic NMR Study

  Chemistry - A European Journal · 2025-11-29

  articleOpen accessSenior authorCorresponding

  ABSTRACT TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy) is a stable radical that is phenomenologically interesting and of high importance in synthesis and catalysis. This radical has been studied extensively with EPR and used as a spin tag for biological materials and to probe hydrogen bonding. The NMR properties of TEMPO have not yet been reported. This contribution describes that all 1 H and 13 C NMR signals of TEMPO are visible in the paramagnetic NMR spectra. The 1 H NMR spectra of TEMPO solutions have a chemical shift range of 50 ppm and require only 8 scans. The 13 C NMR signals are localized within a chemical shift range of 2600 ppm and are obtained within 30 minutes. Samples prepared with different solvents and TEMPO concentrations have been investigated, and it has been demonstrated that all solvents undergo chemical shift changes due to the presence of TEMPO and adduct formation in the case of CDCl 3 . The impact of TEMPO on the 31 P chemical shift of PPh 3 is studied. Higher concentrations of TEMPO in solution lead to narrower signals and the molten substance, measured at 60°C, represents the culmination of this trend. It is demonstrated with paramagnetic solid‐state NMR that TEMPO adsorbs on a silica surface and displays the chemical shift and linewidth features of a dilute solution of TEMPO.

  PublisherOA PDFDOI

• Selective Air Oxidation of Bis- and Trisphosphines Adsorbed on Activated Carbon Surfaces

  Molecules · 2025-06-25 · 2 citations

  articleOpen accessSenior authorCorresponding

  Bis- and trisphosphines incorporating methylene and aryl spacers readily adsorb on the surface of porous activated carbon (AC). The adsorption can be performed in the absence of solvents, even when the phosphines have high melting points, or from solutions. The diverse phosphines Ph2PCH2PPh2 (dppm), Ph2P(CH2)2PPh2 (dppe), Ph2P(CH2)3PPh2 (dppp), Ph2P(p-C6H4)PPh2 (dppbz), and (Ph2PCH2)3CCH3 (tdme) were adsorbed in submonolayers on AC. The adsorbed phosphines were studied by 31P MAS (magic angle spinning) NMR spectroscopy, and their mobilities on the surface were confirmed by determining the 31P T1 relaxation times. All phosphine groups of each bis- and trisphosphine molecule are in contact with the surface, and the molecules exhibit translational mobility as one unit. All phosphines used here are air-stable. Once a submonolayer is created on the AC surface, oxygen from the air is co-adsorbed and transforms all phosphines quantitatively into phosphine oxides at room temperature. The oxidation proceeds in a consecutive manner with the oxidation of one phosphine group after another until the fully oxidized species are formed. Studies of the kinetics are based on integrating the signals in the solution 31P NMR spectra. High temperatures and low surface coverages increase the speed of the oxidation, while light and acid have no impact. The oxidation is fast and complete within one hour for 10% surface coverage at room temperature. In order to study the mechanism and slow down the oxidation, a higher surface coverage of 40% was applied. No unwanted P(V) side products or water adducts were observed. The clean phosphine oxides could be recovered in high yields by washing them off of the AC surface. The oxidation is based on radical activation of O2 on the AC surface due to delocalized electrons on the AC surface. This is corroborated by the result that AIBN-derived radicals enable the air oxidation of PPh3 in solution at 65 °C. When the air-stable complex (CO)2Ni(PPh3)2 is applied to the AC surface and exposed to the air, OPPh3 forms quantitatively. The new surface-assisted air oxidation of phosphines adsorbed on AC renders expensive and hazardous oxidizers obsolete and opens a synthetic pathway to the selective mono-oxidation of bis- and trisphosphines.

  PublisherOA PDFDOI

• Molecular and Immobilized Tripodal Phosphine Ligands and Their Trinuclear Palladium Complexes

  Molecules · 2025-04-04

  articleOpen accessSenior authorCorresponding

  The synthesis and characterization of the tripodal phosphines RSi(CH2CH2PPh2)3 (R = Me, OMe, OEt) (1–3) is described. The 1H NMR spectra of all phosphines display virtual coupling patterns. The ligands form the corresponding trinuclear Pd complexes [RSi(CH2CH2PPh2)3]2(PdCl2)3 (4–6) with three PdCl2 moieties sandwiched between two tripodal ligands. The complexes 4, 5, and 7 (R = OH) have been analyzed by single crystal X-ray diffraction. The coordination at the Pd center is square planar with the phosphine groups occupying trans positions. The 31P{1H} MAS NMR spectra of polycrystalline 1 are in accordance with the packing motif of the molecules in the unit cell. The tripodal ligand 3 has successfully been immobilized on silica as 3i. It coordinates PdCl2 on the surface, as demonstrated by 31P{1H} MAS NMR. Hereby, the cis coordination is prevalent when 3i has maximal surface coverage. At low surface coverage, one tripodal linker can accommodate trans coordination at the metal center. A surface-bound trinuclear Pd complex has been generated, as well as a heterobimetallic Pd/Cu complex. All surface species have been characterized by 31P{1H} MAS NMR.

  PublisherOA PDFDOI

• HRMAS NMR for Studying Solvent‐Induced Mobility of Polymer Chains and Metallocene Migration Into Low‐Density Polyethylene (LDPE)

  Magnetic Resonance in Chemistry · 2024 · 1 citations

  Senior authorCorresponding
  • Chemistry
  • Polymer chemistry
  • Chemical engineering

  time of LDPE is studied. HRMAS allows a quick assessment of metal complexes regarding their ability to penetrate the LDPE network and therefore supports future studies of catalytic polymer degradation.

  PublisherOA PDFDOI

• Solvent-Induced Mobility of Polymer Chains and Solvent-Induced Mobility of Polymer Chains and Metallocene Migration into Ldpe: A Hrmas Nmr Study

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

• Immobilized Di(Hydroperoxy)Propane Adducts of Phosphine Oxides as Traceless and Recyclable Oxidizing Agents

  2023

  1st authorCorresponding
  • Chemistry
  • Combinatorial chemistry
  • Organic chemistry
  PublisherDOI

• Aluminum Trichloride Adducts of Phosphine Oxides: Structures, Solid-State Nmr, and Application

  SSRN Electronic Journal · 2023-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

• CCDC 921482: Experimental Crystal Structure Determination

  The Cambridge Structural Database · 2014-01-01

  datasetOpen accessSenior author

  An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  PublisherDOI

• Easy One‐Pot Synthesis of New Dppm‐Type Linkers for Immobilizations.

  ChemInform · 2005-07-19

  articleSenior author

  Abstract For Abstract see ChemInform Abstract in Full Text.

  PublisherDOI

• Suspension HR-MAS and 14N NMR spectroscopy of neat and immobilized Ionic Liquids for biphasic catalysis

  IrInSubria (University of Insubria) · 2005-01-01

  articleSenior author
  Publisher

Recent grants

• New Strategies for Creating Single and Dual Atom Catalysts on Silica Surfaces

  NSF · $450k · 2019–2023

Frequent coauthors

• F. H. KOEHLER

  Chemnitz University of Technology

  7 shared

• John C. Hoefler

  6 shared

• Maxwell Kimball

  5 shared

• Tuan A. Vu

  Hanoi University of Science and Technology

  4 shared

• Arturo J. Perez

  Mitchell Institute

  4 shared

• Rahym Ashirov

  Texas A&M University

  4 shared

• Nattamai Bhuvanesh

  Texas A&M University

  4 shared

• Michael O'Brien

  Texas A&M University

  4 shared