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Research

Research Interests
Computational organic chemistry DFT and ab-initio methods are used to study principle chemical properties and in conjunction to experiments. Wide range of subjects that are studied and some examples are given here. (a) The nature of aromaticity – one of the principle concepts in organic chemistry which is still not well understood. Within this topic studies of the effect of strain on aromaticity have been carried out, allowing better understanding of the factors governing the aromatic behavior. A new tool (NICS-scan) that assigns diamagnetic and paramagnetic ring currents to molecules was developed. This tool is used to study the nature of compounds and has proved to be useful for assigning any cyclic conjugation (even if not aromatic or antiaromatic). (b) Calculation of CD spectra of chiral compounds. This allows the assignment the absolute configuration of an enantiomer that was experimentally prepared by comparison of the experimental and the calculated CD spectra. In addition to collaborating with experimental chemists, a user friendly code which will allow non-professionals to determine the absolute configuration of an enantiomer and the %ee is being developed. (c) Macrocyclic aromatic compounds, including structural predictions and understanding of unique reactions that these macrocycles undergo are studied computationally. (d) Understanding the factors that govern C-H bond dissociation energies within a unified concept. See list of publication for additional topics. Experimental chemistry Most of the experimental work uses benzocyclobutenes in different directions. The Ni-mediated synthesis of the compounds was developed in the group and allows efficient preparation of different derivatives including bis(cyclobuta)benzenes and tris(cyclobuta)benzene. These compounds are prepared and studied as potential precursors for elusive intermediates (e.g., cyclic C6) and as monomers for the preparation of different highly conjugated polymers.
Read more about the Aroma package

Selected publications

Stanger, A.; Ashkenazi, N.; Shachter, A.; Bläser, D.; Stellberg, P. and Boese, R. “Nickel Mediated Cyclobutabenzenes Syntheses. Trans-7,8-Dibromocyclo- butabenzenes. Their One Pot Preparation, X-ray Structure and Diels Alder Reactions.”, J. Org. Chem., 1996, 61, 2549-2552.Stanger, A; Ashkenazi, N.; Boese, R.; Bläser, D. and Stellberg P. “Hexabromotricyclobutabenzene and Hexabromohexaradialene. Their Nickel Mediated One Pot Syntheses and Crystal Structures.”, Chem. Eur. J. 1997, 3, 208-211.

Stanger, A. “Strain Induced Bond Localization. The Heteroatom Case.”, J. Am. Chem. Soc. 1998, 120, 12034-12040.

Stanger A. “Nucleus Independent Chemical Shifts (NICS). Distance Dependence and Revised Criteria for Aromaticity and Antiaromaticity.”, J. Org. Chem., 2006, 71, 883-893.

Stanger, A. “Can Substituted Cyclopentadienes Become Aromatic or Antiaromatic?”, Chem. Eur. J. 2006, 12, 2745-2751.

Stanger, A. ” The Different Aromatic Characters of Some Localized Benzene derivatives.”, J. Phys. Chem. A. 2008, 112, 12849-12854.

Sason Shaik, Zhenhua Chen, Wei Wu, Amnon Stanger, David Danovich, and Philippe C. Hiberty “An Excursion from Normal to Inverted C-C Bonds Shows a Clear Demarcation between Covalent and Charge-Shift C-C Bonds”, ChemPysChem, 2009, 10, 2658-2669.

Stanger, A. ” What is…..Aromaticity. A Critique of the Aromaticity Concept – Can it Really be Defined?”, an invited feature article, Chem. Commun. , 2009, 1939-1947.

Stanger, A. “Using NICS-scan for quantitative determination of ring currents”, J. Org. Chem.2010, 75, 2281-2288.

The Aroma package

NICS-scan prodedures ((a) J. Org. Chem. 2006, 71, 883-893, (b) J. Phys. Chem. A. 2019, 123, 3922-3927, (c) ChemPhysChem, 2023, 24, e202300080), the σ-only model (J. Org. Chem. 2010, 75, 2281-2288) and the NICS-XY-scan (Chem. Eur. J., 2014, 20, 5673-5688) are useful methods to determine the presence of diatropic and paratropic ring currents, especially those resulting from only the p electrons (aromaticity and antiaromaticity), local and global.
Aroma is a plugin package that has been written by Dr. Anuja Rahalkar (a former post-doctoral fellow in my group) that automates these procedures for using with the Gaussian 09, Gaussian 16, NBO 6, NBO 7, Orca 5 and Orca 6 software packages.
Using Aroma circumvents the need to manually build the appropriate input files and saves the user the difficulty of manually handling vast amounts of numerical data, making the use of the NICS-scans, the σ-only model and NICS-XY-scan easy and accessible.
Aroma 2.0 accepts standard Gaussian and Orca inputs, outputs or checkpoint files as inputs for geometry. It has also the possibility to accept a non-standard input file (see the manual).
It can automatically perform (on request) geometry optimization and a frequencies calculation.
It automatically generates input NICS-scan files for user-defined rings (and bonds and atoms in the case of NICS-XY-scan) using a user-defined BQ (or H: in Orca) range ((defaults are 0-3.9 Å, 2-5 Å) and step size (defaults is 0.1 Å), as well as σ-only input files, and subsequently runs the appropriate Gaussian and Orca jobs.
In addition to the standard Gaussian/Orca output files, Aroma generates text files that contain all the NICS-scan data, and, if NCS and/or σ-only model procedures are requested, also text files that contain the π-MOs contributions to each of the BQs’ chemical shifts and the NICS-scan results for the model. These files can be read by standard software (such as MS-Excel, OriginLab) for the analyses.
Finally, Aroma 2 produced a text file, containing the results of the analysis: For the traditional NICS-scan (reference a) a 3rd degree polynomial fit and the calculation of the NICS(1)p,ZZ value for each of the rings that are studied. For the NICS-scans at higher distances (references b and c) this file contains a two-parameters and three-parameters on-linear line fitting to providing òNICSp,ZZ and NICS(r)p,ZZ for r=1 and 1.7 Å.
Aroma is an open-source program. The (Python 3) source code can be downloaded from github. Stand-alone binary versions for Linux, windows and Mac-OS can be downloaded from this site.

We kindly ask users to fill in the forms (in the download links) before downloading. The e-mail addresses will be served only for updating about new versions and bug fixes.

The manual, including installation instructions, is available for download Aroma 2 manual
To download a Linux-compatible and a Mac-compatible version (source and/or binary) click here.
To download a Windows 11-compatible version (source and/or binary) click here.

Biography

Post doc: Weizmann Postdoctoral Fellow, University of California at Berkeley 1986-1988

Ph.D: Technion, 1985