Project n.1A

Sustainable synthesis of chiral non racemic hydroxyalkanoic acids

Supervisor Prof. Patrizia Nitti email pnitti@units.it

Chiral non racemic hydroxyalkanoic acids are intriguing natural compounds, few can be obtained

from natural feedstocks: they are constituents of bacterial polyhydroxyalkanoates (PHAs),1 and

plant secondary metabolites. Their structure is quite simple, yet they play a crucial role in many

biological processes,2 display anticancer activity,3 and are able to induce gelation of many organic

solvents.4

General structure of hydroxyalkanoic acids

The aim of this project is to synthesise a series of new chiral non racemic hydroxyalcanoic acids

and their derivatives, not achievable from natural precursors, by a procedure that includes an

olefin metathesis step.5,6 Large attention will be payed to carrying out the all organic syntheses

eco-friendly. Chiral non racemic allylic or homoallylic alcohols, the starting material of the

procedure, will be obtained by enzymatic hydrolysis in phosphate buffer solution, and olefin

metathesis reactions will be performed without solvent under microwave irradiation.7 We will

exploit the shift of chain OH group as an alternative approach for tuning the supramolecular

chirality of self-assemblies. Moreover, the interaction with supramolecular chiral scaffolds is a

facile and versatile approach for generating circularly polarized luminescence from non-chiral

fluorophores.8 The possibility of employing a wide array of solvents and fluorophores is quite

promising to afford circularly polarized light across the whole electromagnetic spectrum. Possible

applications are envisaged in advanced and optical technologies and in chiral photochemistry.

1 Shabina Muhammadi; Afzal, M.; Hameed, S. “Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: production, biocompatibility, biodegradation, physical properties and applications” Green Chem. Lett. Rev. 2015, 8, 56–77. 2 Gunstone, F. D. “Fatty Acid and Lipid Chemistry”; Springer: Berlin, 1996 3 Parolin, C.; Calonghi, N.; Presta, E.; Boga, C.; Caruana, P.; Naldi, M.; Andrisano, V.; Masotti, L.; Sartor, G. “Mechanism and stereoselectivity of HDAC I inhibition by (R)-9-hydroxystearic acid in colon cancer” Biochim. Biophys. Acta 2012, 1821, 1334- 1340. 4 Terech, P.; Weiss, R. G. “Low-molecular mass gelators of organic liquids and the properties of their gels” Chem. Rev. 1997, 97, 3133-3159. 5 Grela K. “Olefin Metathesis Theory and Practice”, Published by John Wiley & Sons, Inc., Hoboken, New Jersey, 2014. 6 Boga, C.; Drioli, S.; Forzato, C.; Micheletti, G.; Nitti, P.; Prati F. “An easy route to enantiomerically enriched 7- and 8-hydroxystearic acids by olefin-metathesis-based approach” Synlett, 2016, 27, 1354-1358. 7 Michaut, A.; Boddaert, T.; Coquerel, Y.; Rodriguez. J. “Reluctant cross-metathesis reactions: the highly benecial effect of microwave irradiation” Synthesis, 2007, 2867-2871. 8 Okazaki, Y ; Goto, T.; Sakaguchi, R.; Kuwahara, Y.; Takafuji, M.; Oda, R.; Ihara H. “Facile and versatile approach for generating circularly polarized luminescence by non-chiral, low-molecular dye-on-nanotemplate composite system” Chem. Lett. 2016, 45, 448-450.

Finally, the gelator efficiency of hydroxyl alkanoic acid derivatives will be tested in various

solvents, including green ones, such as dimethyl carbonate, as well as their ability to induce

electronic circular dichroism of host dyes.

Project n.2A

Sustainable catalysis for smart renewable polyesters, (Supervisor prof. Lucia Gardossi email

gardossi@units.it)

The integration of chemistry and biotechnologies contributes to the gradual replacement of petrol-based

chemistry and the development of new platforms of renewable products leading to the closure of carbon

circle. An array of bio-based building blocks is already available at industrial scale and is boosting the

development of new generations of sustainable and functionally competitive polymers. Polylactic acid (PLA)

already represents a successful case, with a capacity of about 180.000 tons/year.

On that respect, biocatalysis already contributes to the selective synthesis, modification and degradation of

bio-based polymers enabling the closure of carbon circle, but also to the in vitro synthesis of advanced

polymers, which are not accessible by chemical routes.

The present project aims at the chemo-enzymatic synthesis of renewable and biodegradable

functionalized polyesters for advanced applications in the biomedical, pharmaceutical, cosmetic,

packaging and environmental applications.

The ultimate aim will be the anchoring - under mild and selective conditions - of bioactive molecules on

the biodegradable, renewable, functionalized polyesters in order to develop smart polymers able to release

bioactive molecules under controlled conditions (e.g. pH) or to confer advanced functions (e.g.

antimicrobial, antioxidant, etc.) to the polymers.

The objective will be achieved by exploiting the internal know-how of the Laboratory of Applied and

Computational Biocatalysis group but also by strengthening on-going international industrial and academic

collaborations, which offer complementary expertise in fields ranging from enzyme engineering to cosmetic

and pharmaceutical formulations. The project will be rooted on robust know how already acquired by the

proponent group and more specifically:

- Know how acquired during the last years of research in the field of selective enzymatic synthesis of

functionalized polyesters (10 published papers on indexed journals and 1 patent)

-Know-how acquired during the FP7-IRENE project concerning bioinformatics methods for in silico

selection of enzymes endowed of desired properties (5 published papers on indexed journals)

-Know-how acquired during the FP5-COMBIOCAT project in the field of chemo-enzymatic synthesis on

solid surfaces (9 published papers on indexed journals and 1 patent)

References

1. Pellis A., et al., “Enzyme-catalyzed functionalization of poly(L-lactic acid) for drug delivery applications”,

Process Biochem., http://dx.doi.org/10.1016/j.procbio.2016.10.014.

2. Pellis, A., et al. “Fully renewable polyesters via polycondensation catalyzed by Thermobifida cellulosilytica

cutinase 1: an integrated approach”. Green Chem., 2017, 2017,19, 490-502.

3. Corici L., et al. “Large scale applications of immobilized enzymes call for sustainable and inexpensive

solutions: rice husk as renewable alternative to fossil-based organic resins.” RSC Adv., 2016, 6, 63256-63270.

4. Corici L. et al. "Understanding potentials and restrictions of solvent-free enzymatic polycondensation of

itaconic acid: an experimental and computational analysis". Adv. Synth. Cat., 2015, 357, 1763-1774.

5. Pellis A., et al. “Towards feasible and scalable solvent-free enzymatic polycondensations: integrating robust

biocatalysts with thin film reactions”. Green Chem., 2015, 17, 1756-1766

Project n.3A

Catalysis for a sustainable development

Ph.D. supervisor: Dr. Tiziano Montini email: tmontini@units.it

The sustainable development of the modern society requires the replacement of fossil compounds as

fuels and raw materials for the production of commodities. In this context, great interest is devoted in the

conversion of cheap and abundant gaseous compounds into high added-value products with the extensive use

of solar light as primary energy source. Among them, the reduction of CO2 or atmospheric N2 into fuels and

fertilizers represent an exciting challenge. The aim of this Ph.D. project is the development of innovative

heterogeneous catalysts to be applied in the conversion of CO2 into fuels (CH4, CO, CH3OH or HCCOH) and

the fixation of N2 into ammonia. The design and synthesis of innovative catalysts will take advantage of the

bottom-up chemical methodologies that allow to control size and shape of the desired products and to

combine different components into final nanocomposite materials. In this way, metal nanoparticles (Pd, Pt,

Au, Ru or their combination), photoactive semiconductors (TiO2, CeO2, metal titanates or calchogenides)

and carbon nanostructures (nanotubes, graphene or graphitic carbon nitride) will be combined in order to

maximize the intimate contact among the components. This a fundamental requisite to promote electron

mobility within the materials, favouring charge separation in photocatalytic reactions and electron transport

in electrocatalytic applications. Post-synthetic treatments (H2 reduction, adsorption of molecular dyes etc.)

will allow the exploitation of visible light, improving the efficiencies of the investigated processes. The

structure and morphology of the synthesized materials will be characterized by advanced microscopy and

spectroscopic techniques, also within a network of collaborations with international research centres. The

functional properties of the materials will be tested in photocatalytic and electrocatalytic reduction of CO2

and N2, opening the possibility of their application in photoelectrocatalytic devices.

Related publications:

Cargnello, M.; Delgado Jaén, J.J.; Hernández Garrido, J.C.; Bakhmutsky, K.; Montini, T.;

Calvino Gámez, J.J.; Gorte, R.J.; Fornasiero, P. "Exceptional Activity for Methane Combustion

over Modular Pd@CeO2 Subunits on Functionalized Al2O3.", Science 2012, 337, 713.

Manfredi, N.; Cecconi, B.; Calabrese, V.; Minotti, A.; Peri, F.; Ruffo, R.; Monai, M.; Romero-

Ocaña, I.; Montini, T.; Fornasiero, P.; Abbotto, A. "Dye-sensitized photocatalytic hydrogen

production: distinct activity in a glucose derivative of phenothiazine dye" Chem.

Commun. 2016, 52, 6977.

Naldoni, A.; Montini, T.; Malara, F.; Mróz, M. M.; Beltram, A.; Virgili, T.; Boldrini, C. L.;

Marelli, M.; Ocaña, I. R.; Delgado, J. J.; Dal Santo, V. and Fornasiero P. "Hot electron

collection on brookite nanorods lateral facets for plasmon-enhanced water oxidation" ACS

Catal. 2017, 7, 1270

Beltram, A.; Melchionna, M.; Montini, T.; Nasi, L.; Prato, M.; Fornasiero, P. "Making H2

from light and biomass-derived alcohols: the outstanding activity of newly designed hierarchical

MWCNTs/Pd@TiO2 hybrid catalysts" Green Chem. 2017, Accepted Manuscript

Project n.4A

DESIGN, SYNTHESIS, ANTIMYCOBACTERIAL ACTIVITY AND INIBITION ASSAY

OF NEW ANTITUBERCULAR DERIVATIVES

SUPERVISORE: Prof. DANIELE ZAMPIERI email: dzampieri@units.it

Tuberculosis (TB) is a debilitating disease that predominantly affects people in developing

countries and it’s in top-10 death causes in worldwide and one of the most serious infectious

illnesses caused by single-pathogen, with 1.8 death cases, 10.4 million new TB cases (2015) and the

epidemic is larger than previously estimated (WHO TB report 2016) (1)

. Moreover, people living

with HIV accounted for 1.2 million (11%) of all new TB cases making treatment ever more

difficult. The responsible pathogen is Mycobacterium tuberculosis (MT) which mainly affects the

lungs, but also other tissues as well as kidneys, eyes, backbone, lever, lymph nodes and meningitis.

Standard therapy consists of a lengthy regimen of antibiotic cocktail (isoniazid-rifampicin-

ethambutol), which though often curative, suffers from poor patient compliance and diminished

effectiveness due to the emergence of drug resistance. Progress in antimycobacterial drug

development is slow and, recently, only two new drugs have been FDA approved (bedaquiline and

delamanid) and, to date, are in advanced phases of clinical development. So, there is a dramatically

need of new molecules gifted with low toxicity in humans and potent antimycobacterial activity, in

particular towards multi-drug resistant strains (MDR).

The aim of his project is to synthesize new antimycobacterial derivatives gifted with a well-defined

mechanism of action. In this respect, several selective MT targets are known and, among them,

DprE1(decaprenylphosphoryl-beta-D-ribose 2’-oxidase)(2)

, alanine-racemase(3)

and Men-B

(menaquinone-B)(4)

. For several years, our research group has been dealing with antimycobacterial

and antifungal drugs targeting cytocrome P450 14-demethylase (CYP-51) and, recently, also new

molecules targeting Men-B.

Among various enzymes, DprE1 is one of the most promising MT target being implicated in

biosynthesis of MT cell-wall. The latter is well known to be highly lipophilic and resistant towards

exogenous substances and the research is focused to develop new DprE1 inhibithors, both gifted

with covalent or non-covalent binding with DprE1 active site. The most interesting compound is

BTZ043(2)

, a nitro benzothiazinone derivative which reached phases of clinical development due to

its high activity against MT (20 fold more active than standard drug, isoniazid). The mechanism of

action od BTZ043 is a “suicide-inhibition-like” due to a covalent binding with the active site in

order to block the epimerization of decaprenyl-phosphoribose (DPR) a decaprenyl-

phosphoarabinose (DPA), an essential process for the cell-wall assembly of MT.

The project aims to synthesize new compounds, i.e. new hybrid molecules, gifted with increased

antimycobacterial activity and with good druggability both versus standard MT H37Rv strain and

MDR strains and, on the other hand gifted with low human toxicity. Enzyme inhibition assay will

also be performing in order to evaluate the ability of the new compounds to interact with the

enzyme active site. Computational studies, performed with molecular modeling technics, will attend

the synthesis of new compounds.

References:

(1)

WHO TB-report 2016 (2)

Makarov V. et al. Science, 2009, 324, 801-804.

(3) Watanabe A., et al. J. Biol. Chem. 2002, 277, 19166-19172.

(4) Li X. et al., Bioorg. Med. Chem. 2010, 20, 6306-6309.

Project n.5A

SHEER AMP MATTERS - Short HEtERochiral AntiMicrobial Peptide nanoMATERials and Reversible Systems

Supervisor: Silvia Marchesan: smarchesan@units.it

Innovative solutions to chemical problems must be cost-effective and reduce the use of agents that persist

in the environment. This project employs short peptides containing amino acids of both handedness, which

self-organise into diverse superstructures (e.g., nanospheres, nanotapes, twisted fibers) in water. The

amyloidogenic diphenylalanine (FF) motif and its derivatives generate superstructures with useful

physicochemical properties (e.g., light responsiveness and ferroelectricity). These structures have high

potential for use in next-generation therapy, diagnosis, and sensing solutions. We have also discovered

tripeptide motifs that self-assemble into amphipathic structures that display mild antimicrobial activity

(while the single molecules do not) and that contain well-defined aqueous regions and hydrophobic

channels, in similar fashion to macromolecular protein complexes, although with the key difference of

striking simplicity. This project will develop a new biologically-relevant supramolecular chemistry of

heterochiral, short peptides. We envisage biomedical relevance in 3 ways: 1) Structural features will be

developed that activate and deactivate a biological function on demand, in situ; 2) We will explore the

largely unknown interactions of these heterochiral supramolecular systems with biological entities, in order

to develop new paradigms of therapeutic intervention; and 3) We will apply the basic knowledge generated

towards solutions to real-world problems, such as antimicrobial hydrogels having a well-defined activity

lifetime. www.marchesanlab.com

References.

1. Curr. Top. Med. Chem. 2016, 16 (18), 2009.

2. Chem. Commun. 2016, 52 (35), 5912.

3. J. Mater. Chem. B. 2015, 3 (41), 8123.

4. Biomaterials 2013, 34 (14), 3678.

Project n.6A

Triterpenes in olive oil: development of analytical methodologies – Supervisor Cristina

Forzato email: cforzato@units.it

Oleanolic and maslinic acids, uvaol and erithrodiol are the main triterpenes in extra virgin olive oil.

It has been shown that they have significant biolgical activity as anti-inflammatory, vasodilating,

antioxidant and anti-tumor. Pomace oil is very rich of triterpenes (average content 2690 mg/Kg),

but according to the EU regulations, it must be refined before being consumed, and this process

leads to the removal of all triterpene acids. Thus virgin olive oil is the only available source of such

compounds in food. Moreover, a recent analysis on 40 cultivars from the World Olive Data Bank of

Cordoba has showm that the profile of the triterpene fraction is an excellent parameter to

characterize monovarietal olive oils.

In this industrial research project, samples from local olive oil producers will be analyzed first with

EU official methods to measure the contents of the four triterpenes. Then new approaches will be

explored, mostly based on NMR (both 1HNMR and 13CNMR) to find simpler ways leading to the

triterpene profile without time requiring sample treatments.

Project n.7A

Development of sensors for olive oil polyphenols – Supervisor Federico Berti email

fberti@units.it

The EU commission has recently established a list of health claims that can be used on the labels of

foods. The health claim for extra virgin olive oil deals with the amount of hydroxytyrosol and

derivatives, which must be at least 5 mg per 20 g of oil. If this condition is satisfied, the producer

may report on the label the health claim on the beneficial effects of phenols. This project is aimed at

obtaining cheap, rapid and user friendly sensors for the recognition of several phenols in olive oil,

to allow the producer to check their level all along the production cycle. In a first step, a set of

molecule capable to interact with phenolic compounds will be identified. Such molecules will be

then exploited as the sensing elements, as they will be used as the active monomers to prepare

imprinted polymeric nanoparticles. Aminoacids and peptides will be considered among other

potential active monomers. The polymeric materials may contain also highly fluorescent

compounds and emit visible light, changing its color or intensity upon binding of the target phenols.

Project n.8A

Development of new components for the construction of metal-mediated multiporphyrin 3D

assemblies (aka: Expand your molecular LEGO™

box!)

Proposer: Prof. Enzo Alessio, Department of Chemical and Pharmaceutical Sciences, UniTs

email: alessi@units.it

The group has a well-established competence in the preparation and characterization of metal-mediated

multiporphyrin 3D assemblies.1 The

porphyrins, functionalized with peripheral

donor groups (e.g. pyridyl rings) are

connected together by appropriately tailored

metal fragments: in Fig. 1 an example of a

2+2 molecular square. Aside from their

structural beauty, often evidenced by

spectacular X-ray structures (see below), such assemblies find interest in host-guest chemistry,

photocatalysis and – in particular – artificial photosynthesis. For most of these potential applications,

solubility in water or – at least – in water mixtures is highly desirable. One strategy for improving water

solubility is that of using highly water-soluble metal connectors.

To date, we have used a relatively small library of metal fragments as connectors between the

porphyrins, most often the Ru(II)-CO precursor shown in Fig. 1. One of the aims of this

project is that of expanding the library of metal connectors, in particular exploiting a

number of newly developed Ru(II)-PTA complexes,2 where PTA (Fig. 2) is an amino-

phosphine ligand that ensures high solubility in water.

Another part of the project aims at preparing new panels

to be used in the higher order self-assembly. In the past

we have largely exploited the zincated molecular square

of porphyrins shown Fig. 3, in which the two zinc atoms

are the connecting points. An example of

supramolecular prism obtained with this flat panel is

shown in Fig. 4, together with its X-ray structure.

Now, we want to insert other metals inside the

square – that make stronger axial bonds compared to

Zn – as well as to prepare new and larger panels,

such as the flat

ones shown below

in Fig. 5. The successful candidate will be involved in: hands-on synthesis (including

microwave-assisted procedures) and characterization of organometallic and

coordination compounds, porphyrins and metallo-porphyrins, and

assemblies thereof. The characterization will involve extensive use of

NMR, UV-vis and fluorescence spectroscopy, and the preparation of X-ray

quality crystals.

Collaborations with other

groups for photophysical and

X-ray structural

characterization of the assemblies are to be expected.

References

1. a) E. Alessio, M. Casanova, E. Zangrando, E. Iengo Chem. Commun. 2012, 48, 5012-5015; b) E. Iengo,

P. Cavigli, D. Milano, P. Tecilla Inorg. Chim. Acta 2014, 417, 59-78; c) S. Durot, J. Taesch, V. Heitz

Chem. Rev. 2014, 114, 8542-8578.

2. F. Battistin, G. Balducci, E. Iengo, N. Demitri, E. Alessio Eur. J. Inorg. Chem. 2016, 2850-2860

Project n.9A

PhD School in Chemistry, UniTS (IT), XXXIII Cycle

PhD Project Title: Metal-containing 3D Supramolecular Discrete Structures.

Supervisor: Prof. Elisabetta Iengo (email: eiengo@units.it).

The project deals with the preparation of cleverly designed metal fragments (coordination compounds and metallo-

porphyrins), and organic units (with a minimum of two peripheral donor sites), to be subsequently used for the

hierarchical construction of 3D discrete architectures with built-in recognition and/or photophysical properties. The

molecular building units will be tailored with appropriate binding characteristics (i.e., available coordination sites and

peripheral donor groups in specific numbers and geometrical arrangements). These features will permit their use in the

efficient assembling of large functional discrete 3D arrays via the complementarity of the reactive sites (e.g. relative

geometry and number, hard/soft and lability/inertness kinetic discriminations), and the establishment of secondary

interactions (e.g. H-bonding, - stacking). The modular approach should ensure for an easier synthetic access to a

wide variety of molecular units, while assuring the transfer of the inherent designed properties of the modules (e.g.

physicochemical, such as solubility, and photophysical, such as absorption/emission/redox activity) to the

supramolecular architectures, and thus a better chance to fine-tune and implement the final functional architectures.

Specific address will be given to 3D discrete multi-porphyrin hollow structures with tunable size/shape of the inner

cavity, for molecular recognition and photo-induced functions [1]. Previous work by us has demonstrated how

combination of a rigid and robust Zn(II)-porphyrin metallacycle (1Zn in the top Figure) with different poly-pyridyl

ligands leads, through axial coordination of the pyridines to the Zn(II) centers of 1Zn, to the efficient self-assembling of

a variety of discrete supramolecular fascinating structures [2]. More recently, the introduction of a H-donor/acceptor

carboxylic moiety on a tri-topic trispyridyl porphyrin has allowed the preparation, at least in the solid state, of a giant

sixteen-porphyrin cage by the contemporary formation of coordinative and H-bonding interactions (the X-ray is shown

on the right of the top Figure ) [3].

An implementation of this approach will involve preparation of novel dimeric porphyrin connectors by means of a

variety of synthetic strategies (bottom Figure), in order to obtain large multiporphyrin containers with increased

stability and sizes. Inorganic, organic and supramolecular synthetic methodologies will be employed for the preparation,

isolation and/or purification of the

molecular units and their derived

structures. The molecular modules,

their assembling process and the

derived supramolecular architectures,

will be thoroughly characterized with

a variety of techniques in solution

(ESI-MS spectrometry, advanced

NMR, UV-vis and emission

spectroscopies, electrochemistry) and

in the solid state (IR spectroscopy and

single crystal X-ray diffraction with

the use of ELETTRA Synchrotron

light radiation source).

The properties of the units and of the

assemblies, with specific regards to

thermodynamics and kinetics of the up-take and release of guests and response to visible light photoexcitation , will be

47.3 Å

monitored with the appropriate techniques, also in collaboration with local, national and foreign research groups. A

minimum six month stay in a foreign research group with complementary scientific expertise is strongly recommended,

in order to increase the project rate of success, expand and differentiate the PhD fellow skills, research methodologies,

as well as working, language, and social environment. [1] S. Durot, J. Taesch, V. Heitz Chem. Rev. 2014, 114, 8542-8578. [2] E. Iengo, P. Cavigli, D. Milano, P. Tecilla Inorg. Chim. Acta 2014, 417, 59-78.

[3] G. Cecot Master Thesis in Chemistry, University of Trieste (IT), A.A. 2013-2014.

Last update: 31.05.2017