Structural Chemistry Core Facility

The Fluorolog-3-22 spectrofluorometer is designed to measure emission and excitation spectra of fluorescence, kinetics of fluorescence, and lifetimes of excited states of molecules. Using of a double monochromator in the excitation and emission channels, super-powerful 450W xenon lamp as a radiation source, and the detection system on the basis of single photon counting results in a very high sensitivity and signal/noise ratio.

The range of excitation wavelengths of the fluorometer is 220-600 nm. The fluorescence emission spectra can be recorded in the 290-850 nm spectral range. The spectrofluorometer is equipped with the fluorescence lifetime measurement system based on time-correlated single photon counting (TCSPC) for measurement of the decay kinetics of the emission in the time range from 1 ns to 0.1 ms.
 

The following accessories are available:

• The Peltier temperature controller working in the temperature range from -10°C to +120°C and temperature controlled sample holder
• The Quanta-φ integrating sphere with fiber optics for direct measurement of the fluorescence quantum yields
• The solid sample holder designed for samples such as films, powders, microscope slides, and fibers
• The liquid nitrogen Dewar assembly for frozen samples
• The set of NanoLEDs for TCSPC, emitting at wavelengths of 280, 295, 340, 405, 440, 460, 470, 560, 590, 610, and 635 nm.
   

Location
Room LS 1141
 

More Information
Spectrofluorometer brochure

Absorption spectroscopy has various applications. It is widely used to study the structure of matter. Analysis of change of the position, intensity and shape of the absorption bands gives the information about changes in the composition and structure of the substances studied. The specificity of absorption spectra of different compounds allows distinguishing them in a mixture. Absorption spectroscopy is particularly effective in the study of processes in liquid media. It is applied for determining concentration of substances in solutions.

The Lambda-35 spectrophotometer operates in the ultraviolet (UV), visible, and infrared (IR) spectral regions covering the spectral range of 190 – 1100 nm with the wavelength accuracy of 0.1 nm. The spectrophotometer can measure absorbance in the range of 0 – 3 absorbance units (AU). It can be operated in both a single-beam and a double-beam configuration. The double-beam mode allows measuring and correcting references.

Lambda-950 is a spectrophotometer with enhanced capabilities. It works in the extended spectral range of 190 – 2500 nm with the wavelength accuracy of 0.08 nm in the UV and visible spectral regions and of 0.3 nm in the IR region. Both a single-beam and a double-beam mode of operation are available.

Lambda-35 and Lambda-950 are user friendly instruments. They are controlled from the UVWinlab software installed on the coupled computer. UVWinlab helps the user to create the measuring task, perform the measurements, analyze and save the results, and create the reports on their basis.

Lambda-35 is equipped with the PTP-1 Peltier Temperature Programmer permitting spectrophotometric measurements at controlled temperatures in the 0 – 100 °C range. The measurements can be performed at constant or variable temperatures. The variable temperature measurements can be programmed at the PTP-1 itself or set up using the Templab software installed on the coupled computer.
 

Location
Lambda-35 and Lambda-950 are located in the rooms LS 1091 and LS 1122, respectively.

Infrared spectroscopy studies the interaction of infrared radiation with matter. Molecules absorb the infrared radiation at frequencies that are characteristic of their structure. An infrared spectrum is a dependence of intensity of the absorbed or transmitted radiation on its frequency or wavelength. Information on the position and relative intensity of the bands in the infrared spectrum is used for making conclusions about structure of the matter under study.

Infrared spectra are recorded on infrared spectrometers. The Spectrum 100 Fourier Transform Infrared Spectrometer (Perkin-Elmer, Inc.) is a bench-top instrument giving fast data collection over a total range of 4000 to 600 cm-1 with a best spectral resolution of 0.5 cm-1.
 

The following sampling accessories are included:

• Universal Attenuated Total Reflectance (ATR) Sampling Accessory for measuring spectra of powders, pastes, gels and liquids; the technique is very efficient; samples are analyzed as they are.
• Diffuse Reflectance Sampling Accessory for collecting spectra from samples of powders, fine particles and highly scattering materials not suitable for transmittance measurements.
• Sample Shuttle Accessory for transmittance IR measurements.
   

Location
The spectrometer is located in room LS 1091.

When linearly-polarized light passes through an optically-active substance, its two circularly polarized components (i.e. the right and left circularly polarized beams of light) travel at different speeds, and are absorbed in differing degrees by the substance. The difference in absorption between the left and right polarized light beams is called circular dichroism (CD).

Circular dichroism spectroscopy is a technique where the CD of molecules under study is measured over a wavelength range. CD spectroscopy is used to study various chiral molecules. A primary use of the technique is analysis of the secondary structure and conformation of macromolecules. In particular, it is an excellent method for the study of the conformations adopted by proteins and nucleic acids in solution.

Jasco-815 spectropolarimeter (Jasco, Inc) is used for CD measurements in liquids in the spectral range of 190 – 900 nm and CD full scale of up to 2000 mdeg. The Peltier temperature controller allows doing the measurements in the 0 - 90°C temperature range. The instrument is controlled from the computer via the Spectra Manager II software.
 

Location
The spectropolarimeter is located in room LS 1141.

InVia Raman spectroscopy is an effective method of chemical analysis and the study of the composition and structure of substances. In the case of Raman scattering, new spectral bands which are not present in the spectrum of the exciting light appear in the spectrum of the radiation scattered by the substance. The frequencies of the new bands are shifted up or down relative to the frequency of the exciting radiation. The shifts give the information about the vibrational modes in the studied system. The number, position, intensity, and polarization of the shifted bands are determined by the molecular structure of the substance.

Raman spectroscopy is used extensively in chemistry for the identification of substances, determination of the individual chemical bonds and groups in the molecules, study intra- and intermolecular interactions, different types of isomerism, phase transitions, and hydrogen bonding.

Because Raman spectroscopy is a sensitive and non-destructive technique, it can be used in forensic applications for detection and analysis of race amounts of a substance without destroying the sample.

In biology and medicine, Raman spectroscopy can be applied for study of structure of proteins, polypeptides, nucleic acids, lipids, oligosaccharides, and biotissues.

InVia Raman microscope (Renishaw, Inc) can be used for obtaining Raman spectra of various liquid, gelatinous, solid, and powder samples. Combination of three lasers allows to cover the wide range of Raman excitation wavelengths in visible – near IR spectral region. Available excitation wavelengths are 406.7, 457, 488, 514, 647, and 785 nm. The wide-range scanning XYZ stage provides the possibility of Raman spectra measuring in different points of the sample with subsequent creation of Raman maps.
 

Location
The Raman microscope is located in the room LS 2068.
 

More Information
Raman microscope brochure

Isothermal titration calorimetry is a technique which is used for measuring the energetics of biochemical reactions or molecular interactions at constant temperature. Experiments are performed by titration of a reactant into a sample solution containing the other reactant(s) necessary for reaction. After each addition, the heat released or absorbed as a result of the reaction is monitored. Thermodynamic analysis of the observed heat effects permits quantitative characterization of the energetic processes associated with the binding reaction. ITC can be used for study of ligand binding phenomena, enzyme-substrate interactions, and interactions among components of multimolecular complexes. The technique allows determination of the binding affinity, stoichiometry, and entropy and enthalpy of the binding reaction in solution.

The Low Volume Nano isothermal titration calorimeter (ITC) from TA Instruments uses two matched reaction vessels. The reference cell contains the buffer and the sample cell contains the reactant dissolved in the same buffer. The injection syringe with a titrant is inserted into the buret which accurately delivers the titrant to the sample cell at specified volumes and intervals. The buret also functions as the stirring mechanism for the reactants in the sample cell when the titrant syringe is installed.

Zero temperature difference is maintained between the sample and reference cell. The power required to maintain this zero difference is used as the calorimeter signal and is monitored as a function of time. If a reaction, producing/absorbing heat occurs in the sample cell, the heat required to maintain the zero difference decreases/increases by the amount of heat supplied/absorbed by the reaction, resulting in a peak in the thermogram.

The sample volume range for the Low Volume NanoITC is 300-700 μl. The injection syringe capacity is 50 μl. The minimum injection volume increment is 0.06 μl. ITC measurements can be performed in the temperature range of 2-80 °C.
 

Location
Room LS 1146
 

More Information
Low Volume NanoITC brochure

DynaPro Titan is a dynamic light scattering (DLS) instrument that can be used for a broad range of applications requiring both accuracy and high sensitivity. It is well suited for studies of nanoparticles, proteins, vesicles, and colloids. The samples have to be filtered to eliminate dust particles, which might interfere with the signal from the molecules being measured. Experimental solution is injected into a quartz cuvette which is placed into the Microsampler module of the instrument and illuminated by the laser.

The specially designed cuvette needs only 12 µl of sample. The scattered light is correlated in the DynaPro host unit which then sends the results to the PC for analysis by the Dynamics software. The DLS size range is 1-1000 nm. The integrated temperature controller allows studying samples at various temperatures ranging from -4°C to 80°C. For protein solutions, the concentration of 1-2 mg/ml is optimal for obtaining the best results.

The DynaPro Titan analyzes the time scale of the scattered light intensity fluctuations by a mathematical process called autocorrelation. To perform the fast data manipulation necessary to obtain results in real time, the DynaPro Titan uses the correlator running special algorithms. The translational diffusion coefficient of the molecules in the sample is determined from the decay of the intensity autocorrelation data. The hydrodynamic radius of the sample is then derived from the translational diffusion coefficient and the weight-average molar mass is calculated.
 

Location
The DLS instrument is located in room LS 1146.

The MBraun Solvent Purification System (SPS) (M.Braun, Inc) removes oxygen and moisture from organic solvents. To remove oxygen from the HPLC grade solvent, the solvent reservoir is purged by the compressed Nitrogen of 99.99% purity. The moisture is removed when the solvent is forced through the circuit of two gas tight stainless steel dessicant columns. Purified solvent which is free of oxygen and moisture is dispensed into a collection vessel under anaerobic conditions by means of the valves located on the front of the system.

Dispensing solvent is a three step process. On the first step, the collection vessel is evacuated to create an anaerobic environment. The second step is the actual dispensing. On the third step the solvent line is cleaned, so solvent does not remain stored there while the system is not in use.
 

The following solvents are available:

• Chlorobenzene
• Diethyl ether
• Dimethyl sulfoxide
• Hexane
• Pentane
• Tetrahydrofuran
• Toluene
   

Location
The solvent purification system is located in the room LS 1141.
 

More Information
Solvent purification system brochure

The Cary 300 is a UV-visible spectrophotometer working in a spectral range of 190 – 900 nm with a large photometric range of up to 6 absorbance units. It is equipped with the Cary Multicell Holder consisting of two sets of six staggered holders. The Multicell Holder is temperature controlled. The temperature may be set from -10 °C to 100 °C (approximately).

The spectrophotometer is controlled by the Cary WinUV software. It consists of several different applications including Scan, Kinetics, Scanning Kinetics, Enzyme Kinetics, RNA/DNA, Simple Reads, and Thermal.
 

Location
Cary 300 is located in the room LS 1146.