Dr. Brian Wagner researches the ability of large, hollow, cage-like “host” molecules to encapsulate other small “guest” molecules. This often increases the fluorescence, or the ability to emit light, of the guests. Real-world applications include enhanced trace analysis of pesticides and the design of molecular sensors.
Postdoctoral Positions:
1990-1992 NSERC Post-Doctoral Fellow, University of Saskatchewan
1993-1995 Reseach Associate, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa
Professional Awards
1998 UPEI Annual Award for Excellence in Teaching
1999 UPEI Annual Award for Outstanding Scholarly Achievement
2000 IUPAC International Conference Travel Award
2005 UPEI Annual Award for Outstanding Scholarly Achievement
2005 3M Canada National Teaching Fellow
Research Interests:
Fluorescence Spectroscopy of Supramolecular Host-Guest Systems
Research Inquiries
Dr. Brian Wagner bwagner@upei.ca
Former Graduate Students
Natasa Stojanovic (M.Sc. 2002)
Lovely Yeasmin (2006)
Patricia Boland (2007)
Saskia Hart (2008)
Current M.Sc. Graduate Students
Stephanie Veenhuis
Carrie Snow
Shawn MacDougall
Former Undergraduate Research Students
Penny MacDonald (Majors 1997)
Greg Gill
Andrew MacRae (Honours 1998)
Christopher MacKinnon (Majors 1999)
Kara Maloney (Majors 1999)
Natasa Stojanovic (Honours 1999)
Jennifer Durber (Honours 2000)
Shannon Fitzpatrick (Honours 2000)
Adam Sherren (Honours 2001)
Greg McManus (Honours 2002)
Debbie Arsenault (Majors 2003)
Matt Rankin (Honours 2003)
Kristin Baglole (Majors 2004)
Mark Perry (Honours 2004)
Stephanie Veenhuis (Honours 2004)
Patricia Boland (Honours 2005)
Laurel Murphy (Honours 2005)
Robert Kern (Honours 2006)
Meagan Smith (Honours 2007)
Carrie Snow (Honours 2007)
Jaclyn O'Brien (Honours 2008)
Current Undergraduate Research Students
Sara Accardi(RISE Scholar; University of Western Ontario)
Jaclyn O'Brien
Wagner Group 2008
Wagner Research Group 2008: Left to right
Shawn MacDougall, Saskia Hart, Carrie Snow, Jaclyn O'Brien, Sara Accardi and Brian Wagner
Research Summary
Investigations of Supramolecular Host-Guest Systems by Fluorescence Spectroscopy
Our group is interested in the study of supramolecular systems using steady-state and time-resolved fluorescence techniques. In particular we are interested in host-guest inclusion complexes, in which an organic guest molecule becomes incorporated inside the internal cavity of a larger, hollow host molecule. This is the simplest example of a supramolecular system, an organization of two or more molecules held together only by intermolecular forces, such as van der Waals forces and hydrogen bonding. This simple complexation is illustrated in the picture below.
The host molecules of interest are all large, cage-like organic molecules, with well-defined nonpolar internal cavities; the specific hosts of interest in our group are described below. In order to study these complexes, we choose polarity sensitive fluorescence probes as guests. Such guests include the well-known anilinosulphonate fluorescent probes, such as 1,8-ANS and 2,6-ANS, amongst others. These probes in general show an extreme sensitivity of their fluorescence to the polarity of their local environment. In most cases, these probes are extremely fluorescent in nonpolar media, but nearly non-fluorescent in a polar medium. Since all of our work is done in the aqueous phase, and all of the hosts of interest contain relatively nonpolar internal cavities, the probes become much more fluorescent when incorporated into the host than when free in solution. Thus, a large fluorescence enhancement is observed upon formation of the host-guest complex. This fluorescence enhancement is easily measured by steady-state fluorescence spectroscopy, providing us with an accurate and sensitive method for studying these systems. A variety of important information can be obtained, such as the nature of the specific interactions, the complexation equilibrium constant K, and DG, DH, and DS for the complexation process. It is also possible to obtain properties of the host molecule itself, such as the polarity of the internal cavity.
In addition to the use of the observed fluorescence changes for the study of the complexation process, some of these changes have potential applications in the fields of molecular recognition and trace analysis. If the fluorescent guest is a molecule of environmental (or other) interest, such as PCBs or pesticides, then addition of an appropriate host molecule may increase the observed fluorescence, resulting in an improved sensitivity of the trace fluorescence detection of these compounds. Furthermore, such a fluorescent system could be used simply to detect the presence of specific molecules, and thus serve as a sensitive molecular sensor.
Our work has been focused on the investigation of the inclusion complexes of three families of host molecules, namely cyclodextrins, cucurbituril, and calixarenes. All of these hosts are large, hollow organic molecules, with well-defined internal cavities capable of including smaller guest molecules.
Cyclodextrins (CDs). These large cyclic oligosaccharides have an overall bucket shape, into which organic species can become incorporated. There are three common CDs: a, b, and g, which contain 6, 7, or 8 monomers, respectively. These have cavity sizes of 5.7, 7.8, and 9.5 Å, allowing for differential complexation of molecules of different sizes. We are also interested in derivatized CDs, in which some of the hydroxyl hydrogens have been replaced by other groups, such as methyl or hydroxypropyl groups. These modified CDs have an even greater potential for fluorescence enhancement than their unmodified parents. In some cases, we have found that modified s-cyclodextrins can enhance the intensity of a fluorescence probe by a factor of 180 times! This has definite potential applications, in the use of fluorescence materials, and in the use of fluorescence as a detection technique. Publications # 28 and 30 deal with modified CDs.
Cucurbituril Cucurbituril is a unique cage compound, consisting of a C, N s-framework. Cucurbituril is extremely rigid, with a well-defined internal cavity. The cavity is relatively small, with an internal diameter of 5.5 Å, accessible by openings of only 4.0 Å. This molecule thus has tremendous potential as a selective host. It has been shown to have an exceptional ability to encapsulate alkylammonium ions. More recently, it has also been shown to encapsulate neutral organic compounds. We have been working on studying host-guest complexes of cucurbituril by fluorescence spectroscopy. Publication # 31 describes a fluorescent solid containing cucurbituril and the fluorescent probe 1,8-ANS.
Calixarenes. Calix[n]arenes are macrocyclic oligomers of phenol, usually consisting of 4, 6, or 8 monomer units (n). They contain a large hydrophobic cavity, and are thus analogous to cyclodextrins, but with two major differences: 1) the internal cavity is lined by the p-electrons of the aromatic rings, in contrast to the purely s-framework of cyclodextrins; and 2) only one rim is lined by hydroxyl groups, and the rings are linked by methylene bridges, which results in a much greater rotational freedom of the individual rings. Thus, calixarenes have a very different type of internal cavity, and a much greater range of possible conformers (and therefore cavity size and shape), as compared with cyclodextrins. Their supramolecular host properties can therefore be expected to be distinctive. For example, two distinct stable conformations of a general calix[4]arene are shown above. We are now studying calixarene host-guest complexes using fluorescence spectroscopy.
Publications in Refereed Journals or Book Series
Ternary Complexes Comprising Cucurbit[10]uril, Porphyrins, and Guests. Simin Liu, Atinddra D. Shukla, Brian D. Wagner. Angel E. Kaifer and Lyle Isaacs. Angew. Chem. Int. Ed. 47, 2657 (2008).
Exciplex fluorescence in coordination polymers of Zn2+ and 4,4’-bipyridine containing intercalated pyrene and enclathrated aromatic solvent guests. Gregory J. McManus, John J. Perry IV, Mark Perry, Brian D. Wagner and Michael J. Zaworotko. Journal of the American Chemical Society 129, 9094-9101 (2007).
Molecular Recognition Properties of a Water Soluble Cucurbit[6]uril Analogue, Jason Lagona, Brian D. Wagner and Lyle Isaacs, Journal of Organic Chemistry, 71, 1181 (2006).
Novel Pyrene and 8-Anilino-1-naphthalenesulfonic Acid-MoS2 Intercalates. Rabin Bissessur, Brian D. Wagner, and Ralf Brüning. J. Mater. Sci. 39, 110 (2004).
Fluorescence Suppression of 7-Methoxycoumarin upon Inclusion into Cyclodextrins. Brian D. Wagner, Shannon J. Fitzpatrick, and Gregory J. McManus. J. Incl. Phenom. Macro. Chem. 47, 187 (2003).
Host Properties of Cucurbit[7]uril: Fluorescence Enhancement of Anilinonaphthalene Sulfonates. Brian D. Wagner, Natasa Stojanovic, Anthony I. Day, and Rodney J. Blanch. J. Phys. Chem. B 107, 10741 (2003).
A Spectroscopic and Molecular Modelling Study of the Nature of the Association Complexes of Nile Red with Cyclodextrins. Brian D. Wagner, Natasa Stojanovic, Gaetan Leclair and Christophe K. Jankowski. J. Incl. Phenom. Macro. Chem. 45, 275 (2003).
Enhancement of the Fluorescence and Stability of O-Phthalaldehyde-Derived Isoindoles of Amino Acids Using Hydroxypropyl- -Cyclodextrin. Brian D. Wagner and Gregory J. McManus. Anal. Biochem. 317, 233 (2003)
Fluorescence Studies of Supramolecular Host-Guest Inclusion Complexes. Brian D. Wagner, Chapter 1 in Handbook of Photochemistry and Photobiology, H. S. Nalwa, Ed., American Scientific Publishers, Los Angeles (2003), Volume 3, pp. 1-58.
Amination of Pyridylketenes: Experimental and Computational Studies of Strong Amide Enol Stabilization by the 2-Pyridinyl Group. Austin W. Acton, Annette D. Allen, Luis M. Antunes, Andrei V. Federov, Katayoun Najafian, Thomas T. Tidwell and Brian D. Wagner. J. Am. Chem. Soc. 124, 13790 (2002).
Exciplex Fluorescence of ([Zn(bipy)1.5(NO3)2.CH3OH].0.5pyrene}n:A Coordination Polymer Containing Intercalated Pyrene Molecules. Brian D. Wagner, Gregory J. McManus, Brian Moulton, and Michael J. Zaworotko, Chem. Commun. 2176 (2002).
Cyclodextrin-, UV- and High pH-Induced Fluorescence Enhancement of the Pesticide Aziniphos-methyl: Applications to its Trace Analysis. Brian D. Wagner, Adam C. Sherren, and Matthew A. Rankin. Can. J. Chem. 80, 1210 (2002).
A Fluorescent Host-Guest Complex of Cucurbituril in Solution: A Molecular Jack O'Lantern. Brian D. Wagner, Shannon J. Fitzpatrick, Monica A. Gill, Andrew I. MacRae, and Natasa Stojanovic. Canadian Journal of Chemistry 79, 1101 (2001).
A Comparison of the Host-Guest Inclusion Complexes of 1,8-ANS and 2,6-ANS in Parent and Modified Cyclodextrins. Brian D. Wagner and Shannon J. Fitzpatrick. J. Incl. Phenom. Macro. Chem. 38, 467 (2000).
A Visual Demonstration of Supramolecular Chemistry: Observable Fluorescence Enhancement upon Host-Guest Inclusion. Brian D. Wagner, Penny J. MacDonald, and Maryam Wagner. Journal of Chemical Education 77, 178 (2000).
The Lattice Inclusion Compound of ANS and Cucurbituril: A Unique Fluorescent Solid. Brian D. Wagner and Andrew I. MacRae. Journal of Physical Chemistry B, 103, 10114 (1999).
6-Oxocyclohexa-2,4-dienylideneketene: A Highly Reactive -Oxoketene. Regina C.-Y. Liu, Janusz Lusztyk, Michael A. McAllister, Thomas T. Tidwell, and Brian D. Wagner. Journal of the American Chemical Society 120, 6247 (1998).
The Fluorescence Enhancement of 1-Anilinonaphthalene-8-Sulfonate (ANS) by Modified-Cyclodextrins. Brian D. Wagner and Penny J. MacDonald. Journal of Photochemistry and Photobiology A: Chemistry 114, 151 (1998).
Spectroscopy and Absolute Reactivity of Ketenes in Acetonitrile Studied by Laser Flash Photolysis with Time-Resolved Infrared Detection. Brian D. Wagner, Bradley R. Arnold, Gerald S. Brown, and Janusz Lusztyk. Journal of the American Chemical Society 120, 1827 (1998).
Generation of 1,2-Bisketenes from Cyclobutene-1,2-diones by Flash Photolysis and Ring Closure Kinetics. Annette D. Allen, Jim D. Colomvakos, François Diederich, Ian Egle, Xiaokuai Hao, Ronghua Liu, Janusz Lusztyk, Jihai Ma, Michael A. McAllister, Yves Rubin, Kuangsen Sung, Thomas T. Tidwell, Brian D. Wagner and Da-chuan Zhao. Journal of the American Chemical Society.119, 12125 (1997).
Reactivity of Dibenzofulveneketene Towards Amines. A Laser Flash Photolysis Study with Ultraviolet and Infrared Detection. N.C. de Lucas, J.C. Netto-Ferreira, J. Andraos, J. Lusztyk, B.D. Wagner, J. Lusztyk, and J.C. Scaiano. Tetrahedron Letters 38, 5147 (1997).
3-1,3,4-Oxadiazolines: Photochemical Precursors to Diazoalkanes and sec-Alkanediazonium Ions in Acidic Solution. John Paul Pezacki, Brian D. Wagner, Calvin S.Q. Lew, John Warkentin, and Janusz Lusztyk. Journal of the American Chemical Society 119, 1789 (1997).
Detection and Characterization of a Transient Zwitterion, the 9-Carboxylate-9-fluorenyl Cation, and its Conjugate Acid. C.S.Q. Lew, B.D. Wagner, M.P. Augelini, E. Lee-Ruff, J. Lusztyk, and L.J. Johnston. Journal of the American Chemical Society 118, 12066 (1996).
Electronic Absorption and Luminescence. Linda J. Johnston and Brian D. Wagner, Chapter 13 in Physical Methods in Supramolecular, J. Eric D. Davies and J. Ripmeester, Eds., Pergamon Press, Oxford, UK, 1996 (Volume 8 of Comprehensive Supramolecular Chemistry). Chemistry
Absolute Kinetics of Piperidinium Radical Reactions with Olefins in Acetonitrile Solution. Brian D. Wagner, G. Ruel, and Janusz Lusztyk. Journal of the American Chemical Society 118, 13 (1996).
Evidence for Molecular Distortion Involving the Carbonyl Group in Triplet States of Carbonyl Derivatives of Naphthalene Obtained from Time Resolved Vibrational Spectroscopic Studies. M.J. van der Burgt, A.H. Huizer, C.A.G.O. Varma, B.D. Wagner, and J. Lusztyk. Chemical Physics 196, 193 (1995).
Kinetic and Theoretical Studies of Ring Closure of Unstabilized Bisketenes to Cyclobutenediones. Annette D. Allen, Jim D. Colomvakos, Ian Egle, Janusz Lusztyk, Michael A. McAllister, Thomas T. Tidwell, Brian D. Wagner and Da-chuan Zhao. Journal of the American Chemical Society 117, 7552 (1995).
Subpicosecond Vibrational Relaxation of the S1 States of Azulene and Guaiazulene in Solution. Dietrich Tittlebach-Helmrich, Brian D. Wagner, and Ronald P. Steer. Canadian Journal of Chemistry 73, 303 (1995).
Azidyl Radical Reactivity. N6·- as a Kinetic Probe for the Addition Reactions of Azidyl Radicals with Olefins. Mark S. Workentin, Brian D. Wagner, Janusz Lusztyk, and Danial D.M. Wayner. Journal of the American Chemical Society 117, 119 (1995).
N6·-. Spectroscopic and Theoretical Studies of an Unusual Pseudohalogen Radical Anion. Mark S. Workentin, Brian D. Wagner, Fabrizia Negri, Janusz Lusztyk, Willem Siebrand, and Danial D.M. Wayner. Journal of Physical Chemistry 99, 94 (1995).
Phenylynol, PhCCOH: First Detection in Solution via Time-Resolved Infrared. Brian D. Wagner, Marek M. Zgiersky, and Janusz Lusztyk. Journal of the American Chemical Society 116, 6433 (1994).
Perturbative Treatments of Pump-Probe Laser-Molecule Interactions with Applications to Azulene and Trimethylazulene. Phuc Tran, William J. Meath, Brian D. Wagner, and Ronald P. Steer. Journal of Chemical Physics 100, 4165 (1994).
The Effect of Solvent Viscosity on the Population Relaxation Times of the S1 States of Azulene and Related Compounds. Dietrich Tittlebach-Helmrich, Brian D. Wagner, and Ronald P. Steer. Chemical Physics Letters 209, 464 (1993).
Sub-Picosecond Pump-Probe Measurements of the Electronic Relaxation Rates of the S1 States of Azulene and Related Compounds in Polar and Nonpolar Solvents. Brian D. Wagner, Marek Szymanski, and Ronald P. Steer. Journal of Chemical Physics 98, 301 (1993).
Radiationless Decay of the S2 State of Azulene and Related Compounds: Solvent Dependence and the Energy Gap Law. Brian D. Wagner, Deitrich Tittelbach-Helmrich, and Ronald P. Steer. Journal of Physical Chemistry96, 7904 (1992).
Recovery of Fluorescence Lifetime Distributions: Application to Förster Transfer in Rigid and Viscous Media. Brian D. Wagner and William R. Ware. Journal of Physical Chemistry 94, 3489 (1990).
A Comparison of the Maximum Entropy and Exponential Series Methods for Recovery of Distributions of Lifetimes from Fluorescence Decay Data. Aleksander Siemiarczuk, Brian D. Wagner, and William R. Ware. Journal of Physical Chemistry 94, 1661 (1990).
Recovery of Fluorescence Lifetime Distributions Generated by Heterogeneous Systems. A. Siemiarczuk, B.D. Wagner, and W.R. Ware. Proceedings of the Society of Photo-optical Instrumentation Engineers (SPIE) 1054, 54 (1989).
Recovery of Underlying Distributions of Lifetimes from Fluorescence Decay Data II. D.R. James, Y.-S. Liu, A. Siemiarczuk, B.D. Wagner, and W.R. Ware. Proceedings of the Society of Photo-optical Instrumentation Engineers (SPIE) 909, 90 (1988).
Distributions of Fluorescence Decay Times for Parinaric Acids in Phospholipid Membranes. D.R. James, J.R. Turnbull, B.D. Wagner, W.R. Ware, and N.O. Petersen. Biochemistry 26, 6272 (1987).
Fluorescence Lifetime Distribution in Homotryptophan Derivatives. Brian D. Wagner, Douglas R. James, and William R. Ware. Chemical Physics Letters 138, 181 (1987).
Recovery of Underlying Distributions of Lifetimes from Fluorescence Decay Data. D.R. James, Y.-S. Liu, N.O. Petersen, A. Siemiarczuk, B.D. Wagner, and W.R. Ware. Proceedings of the Society of Photo-optical Instrumentation Engineers (SPIE) 743, 117 (1987).
A Calorimetric Investigation of Polymorphism in a Layered Perovskite, KALF4. Mary Anne White and Brian D. Wagner. Journal of Chemical Thermodynamics 18, 519 (1986).
The Nature of Ammonium Ion Disorder in Ammonium Tetrafluoro-aluminate, NH4AlF4. Mary Anne White and Brian D. Wagner. Journal of Chemical Physics 83, 5844 (1985).
Two-Dimensional Hindered Internal Rotations in Activated Complexes of the Form XH2. Philip D. Pacey and Brian D. Wagner. Journal of Chemical Physics 80, 1477 (1984).
Department of Chemistry | K C Irving Building
tel. 902-566-0314 | fax. 902-566-0632 | email. chemistry@upei.ca
