Session IVB

Tuesday, May 17th

Session IVB: 


Coordination Driven Self-Assembled Cofacial Catalysts for Oxygen Reduction

Amanda Oldacre and Timothy R. Cook

University at Buffalo, Department of Chemistry

The large kinetic barriers associated with redox chemistry of relevance to energy storage can be circumvented by catalytic pathways. Cofacial catalysts that are capable of small molecule activation allow for preorganization of transition states and enable two or more metals to participate, which decreases the demand on a single metal center.  Metalloporphyrins can be assembled into a cofacial conformations using molecular clips that enforce an offset between the two macrocycles. Herein, we describe a system that assembles cobalt 5,10,15,20–tetra(4–pyridyl) porphyrins (Co–TPyP) with diruthenium clips to furnish [Ru86–p–PriC6H4Me)8(Co–TPyP)2(C6H2O4)4](O3SCF3)8 (Co prism). Catalytic activity towards the reduction of oxygen is shown in both Co–TPyP and the Co prism. This work encompasses the electrochemical oxygen reduction by homogeneous solutions of Co–TPyP and Co prism. 



Quantifying Analyte-Porous Silicon Interactions

Ari Darlow, Justin M. Reynard, Dustin T. McCall, and Frank V. Bright

University at Buffalo, Department of Chemistry

Porous silicon (pSi) has been studied for use in chemical sensing. Key to the success of such a strategy is understanding and selectively controlling analyte-pSi interactions. In this research I have been using the intrinsic pSi photoluminescence (PL) to determine the analyte-dependent PL response from as prepared, oxidized and silanized pSi. This presentation will describe our measurement system and strategy and summarize the analyte-pSi thermodynamics we have measured to date.



Novel Magnetic Composite Materials: Metal-Organic Frameworks as Hosts for Molecular Nanomagnets

Darpandeep Aulakh, Joshua B. Pyser, Xuan Zhang, Andrey A. Yakovenko, Kim R. Dunbar, and Mario Wriedt

Clarkson University

Next-generation computer technologies will require ultrahigh-density data storage devices and quantum computing based on isolated spin-carriers, so-called molecular spintronics.1 Single-molecule magnets (SMMs) have shown great potential for such applications.2 Their unique magnetic properties enable SMMs to be used in spintronics for switching from total spin up to total spin down on a molecular level, and therefore each molecule can be used as a magnetic bit of information. Although a broad community works on the design of new SMMs with improved properties,3 coupling of the nanoscale units to the macroscopic world remains as a key challenge.4 Any practical application of SMMs requires in the first step their organization in 2D or 3D networks to allow read-and-write processes. Moreover, they are very delicate molecules that break down easily and thus, they need to be protected to retain their unique magnetic properties. Owed to their crystalline nature and tunability, metal-organic frameworks (MOFs) provide an excellent means to overcome this challenge. We investigated the unprecedented incorporation of SMMs into multidimensional MOF matrixes, yielding new nanostructured composite materials that combines key SMM properties with the functional properties of MOFs. We believe that these findings might be crucial for the development of spintronics in real world applications. In this presentation we will focus on the fundamental understanding in the exciting structure-property relationships of these SMM@MOF composite materials.

 (1)        Sanvito, S. Chem. Soc. Rev. 2011, 40, 3336.                                                                                                                                                        (2)        Bogani, L.; Wernsdorfer, W. Nat Mater 2008, 7, 179.                                                                                                                                                (3)        Woodruff, D. N.; Winpenny, R. E. P.; Layfield, R. A. Chem. Rev. 2013, 113, 5110.                                                                                                    (4)        Domingo, N.; Bellido, E.; Ruiz-Molina, D. Chem. Soc. Rev. 2012, 41, 258.


CdSe/β-Pb0.33V2O5 Heterostructures:  Nanoscale Semiconductor Interfaces with Tunable Energetic Configurations for Solar Energy Conversion and Storage

Christoper Milleville, Kate E. Pelcher, Sarbajit Banerjee, and David F. Watson

University at Buffalo, Department of Chemistry

Achieving directional charge transfer across semiconductor interfaces requires careful consideration of relative band alignments. Simple binary semiconductors that have been studied for photovoltaics have clearly defined valence and conduction band edges and are difficult to reconfigure, thereby establishing limitations on tunability of the thermodynamic driving force. One alternative is to strategically position electronic states in a semiconductor through the introduction of dopants or midgap states. In this seminar, a promising tunable platform for light harvesting and excited-state charge transfer based on interfacing β-Pb0.33V2O5 nanowires (having intrinsic midgap states) with CdSe quantum dots will be presented. Two distinct routes are developed for assembling the heterostructures: linker-assisted assembly mediated by a bifunctional ligand and successive ionic layer adsorption and reaction (SILAR). High-energy valence band X-ray photoelectron spectroscopy measurements indicate that midgap states of the β-Pb0.33V2O5 nanowires are closely overlapped in energy with the valence band edges of CdSe quantum dots. Transient absorption measurements show that the midgap states in β-Pb0.33V2O5 can mediate directional charge transfer of both electrons and holes from photoexcited CdSe quantum dots (QDs) to the CB and midgap states of β-Pb0.33V2O5, respectively.


Investigation of PBDE-47 and its Hydroxylated Analog, 5-OH-BDE-47, in Humans: Metabolic or Environmental Impact?

Austin Quinn and Joseph Gardella Jr.

University at Buffalo, Department of Chemistry

Soft hydrophilic polymers are tailored to uptake and deliver  growth factor proteins. Protein uptake is measured by near edge X-ray emission fine structure NEXAFS spectra for HEMA treated with varying protein treatment times. As well the soft X-ray microscope at the Canadian light source can generate images in order to map the degree of protein uptake in the image of a cross section.  The diffusion is also characterized using time of flight secondary ion mass spectrometry TOF-SIMS. These two techniques have found continued use in our lab, which provides characterization of specialized materials and chemical mapping in. The work discussed in this presentation is a report of an ongoing R&D collaboration between the Gardella lab, UB Medical School, and Roswell Park Cancer Research Institute, collectively referred to as the tissue engineering group. The group has focused on developing specialized polymeric materials for medical applications and devices. This specific material differs from our traditional HEMA membrane in that it has undergone a surface optimization in order to prevent excessive transpiration of moisture from the material.