This tutorial review is addressed to readers with a background in basic organic chemistry and spectroscopy, but without a specific knowledge of electronic circular dichroism. It describes the fundamental principles, instrumentation, data analysis, and different approaches for interpretation of ECD. The discussion focuses on the application of ECD, also in combination with other methods, in structural analysis of organic compounds, including host-guest complexes, and will emphasize the importance of the interplay between configurational and conformational factors. The tutorial also covers modern supramolecular aspects of ECD and recent developments in computational methods.

A new cyclohexenone (1) and a new caffeoyl ester derivative (2), together with the known compounds (-)-isolariciresinol 3-alpha-O-beta-D-glucopyranoside (3), (+)-1-hydroxypinoresinol 1-O-beta-D-glucopyranoside (4), isoacteoside (5), luteolin 4'-O-beta-D-glucopyranoside (6), and indole-3-carboxylic acid (7), were isolated from the leaves of Bauhinia tarapotensis. The structures of these new compounds were determined by spectroscopic data analysis. The antioxidant activities of 1-7 were determined by measuring their free radical scavenging effects, using the 1,1-diphenyl-2-dipicrylhydrazyl free radical (DPPH) and Trolox equivalent antioxidant activity (TEAC) methods, and the coupled oxidation of beta-carotene and linoleic acid. Compounds 3-5 showed good activities in the DPPH and TEAC tests, while compounds 1 and 2 were active in the coupled oxidation of beta-carotene and linoleic acid bioassay.

Lanthanide (III) luminescence is very characteristic: it is characterized by narrow emission bands, large Stokes shift, and a long excited state lifetime. Moreover, chiral lanthanide complexes can emit strongly circularly polarized light in a way that is almost precluded to purely organic molecules. Thanks to the sensitivity and specificity of the Ln circularly polarized luminescence (CPL) signal, CPL-active complexes are therefore employed as bioanalytical tools and other uses can be envisaged in many other fields. Here we present a brief overview of the most recently developed CPL-active lanthanide complexes and a selected few examples of their applications. We briefly discuss the main mechanisms that can rationalize the observed outstanding CPL properties of these systems, and some practical suggestions on how to measure and report data.

Chiral π-conjugated molecules provide new materials with outstanding features for current and perspective applications, especially in the field of optoelectronic devices. In thin films, processes such as charge conduction, light absorption, and emission are governed not only by the structure of the individual molecules but also by their supramolecular structures and intermolecular interactions to a large extent. Electronic circular dichroism, ECD, and its emission counterpart, circularly polarized luminescence, CPL, provide tools for studying aggregated states and the key properties to be sought for designing innovative devices. In this review, we shall present a comprehensive coverage of chiroptical properties measured on thin films of organic π-conjugated molecules. In the first part, we shall discuss some general concepts of ECD, CPL, and other chiroptical spectroscopies, with a focus on their applications to thin film samples. In the following, we will overview the existing literature on chiral π-conjugated systems whose thin films have been characterized by ECD and/or CPL, as well other chiroptical spectroscopies. Special emphasis will be put on systems with large dissymmetry factors (g abs and g lum) and on the application of ECD and CPL to derive structural information on aggregated states.

An increasing number of circularly polarized luminescence (CPL) molecular emitters has been developed in recent years and many of them are intended for applications in which high overall CPL efficiencies are required. In order to have a complete picture of the efficiency of a CPL emitter, dissymmetry factor (glum) is not enough. In the following we propose a new quantity, named CPL brightness (BCPL), which takes into account absorption extinction coefficient and quantum yield along with the glum factor. We calculated BCPL value for more than 180 compounds reported in the literature and we analyse data distribution for the main classes of CPL molecular emitters. This tool can be employed to put into context new CPL active compounds and to direct the choice of molecular systems for specific CPL applications.

The first circularly polarized OLED (CP-OLED) based on a chiral lanthanide complex is developed. With a simple architecture, this proof-of-concept device attains the highest polarization reported so far and additionally presents the first example of a Ln-based OLED that can be turned into a CP-OLED, fully retaining the special features of Ln-based OLEDs.

The electronic circular dichroism (ECD) spectra of flexible molecules include the contributions of all conformers populated at the working temperature. ECD spectra of chiral substrates depend on their stereochemistry in terms of both absolute configuration, as reflected in the sign of the spectrum, and molecular conformation, which dictates the overall spectral shape (possibly including the sign) in a very sensitive manner. The unique high sensitivity of ECD towards conformation, as well as of other chiroptical spectroscopies, renders these techniques a useful alternative or complement to standard spectroscopic tools for conformational investigations, such as NMR. This tutorial review provides first a brief discussion of the main principles of ECD spectroscopy and related methods for interpretation of spectra, with special reference to conformational aspects. The review focuses on the common problems encountered in the application of ECD for assignments of absolute configuration of flexible molecules. These problems can be handled either by taking into account the whole conformational ensemble or by considering rigid derivatives prepared ad hoc. Finally, the review presents the relatively less common but very interesting application of ECD spectroscopy for conformational analyses of organic compounds.

The method employing dimolybdenum tetraacetate for the assignment of the absolute configuration of optically active 1,2-diols is thoroughly revisited and applied to several compounds, some of which were synthesized by asymmetric cis-dihydroxylation. No exceptions were found to the empirical rule relating the sign of the induced CD spectrum and the configuration of the substrate, whatever its structure and sterical requirements. To broaden the scope of the method, its applicability to critical situations commonly encountered with synthetic products is tested. It is demonstrated that the method can be applied on samples with low chemical and optical purity, and that it may lend itself as a means to estimate the ee. The roles of the water content of the sample and of the diol-to-dimolybdenum ratio are investigated.