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Special Issue "Small Molecules: Structure and Activity - Theme Issue Honoring Prof. Kalevi Pihlaja on His 80th Birthday"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (30 September 2020).

Special Issue Editors

Prof. Ferenc Fulop
Website
Guest Editor
Institute of Pharmaceutical Chemistry, University of Szeged, Hungary
Interests: heterocyclic chemistry; stereochemistry; medicinal chemistry; green syntheses; flow chemistry
Prof. Dr. Dariusz Matosiuk
Website
Guest Editor
Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Faculty of Pharmacy, Medical University of Lublin, Lublin, Poland
Interests: medicinal chemistry; synthesis of heterocyclic compounds; structural elucidation of heterocyclic compounds; molecular modeling; functional activity of small molecules; GPCRs; transmembrane and cellular kinases; pain; allosteric modulation

Special Issue Information

Dear Colleagues,

text

Professor Kalevi Pihlaja

A Tribute

Kalevi Pihlaja was born on February 13, 1940, in the small Western Finnish town of Aura on the beautiful river Aurajoki. His family soon moved to another little Western Finnish town, Mellilä, where he spent his youth until he was eighteen. After the secondary and high schools at Elisenvaara Lyceum in the village Kyrö of the town Karinainen, he graduated in 1958 and carried out his Navy service in Turku (1958–1959). Since then, his life has been tightly bound in nearby Turku, the oldest city of Finland, and to the University of Turku. After defending his thesis in physical organic chemistry in 1967, he was appointed Docent in Physical Organic Chemistry at the University of Turku, followed by election to an Associate Professorship in Organic Chemistry in 1971. He served as Visiting Professor at Stirling University, Scotland, in 1973–1974, carrying out structural studies on various heterocycles by NMR and at the New York State University College at Potsdam in 1977–1978, concentrating again on structural studies, especially with MS, as well as going to meet his friends and deliver lectures (in 22 places altogether). When in Potsdam, he was elected to a full Professorship in Physical Chemistry at the University of Turku in 1978. From 1981 to 1986, Professor Pihlaja served as Dean of the Faculty of Mathematics and Natural Sciences. At the same time, he served as a Member of the Committee of Natural Sciences of the Academy of Finland.

Professor Kalevi Pihlaja is one of the founding fathers of physical organic chemistry in Finland and in Northern Europe. His pioneering work in reaction kinetics and thermochemistry initiated the use of a quantitative approach in the description of the reactivity of organic compounds. This work soon extended to novel methods in the structural and conformational analysis of molecules. During 1971–2008 Professor Pihlaja developed a world-leading laboratory in structural chemistry, famous for top-class work in mass spectrometry and NMR structural analysis. The scientific excellence of Professor Pihlaja and his group attracted organic chemists from many countries to Turku. In particular, mention should be made of the long-time collaboration with synthetic chemists from Hungary (Albert Szent-Györgyi Medical University and Joszef Attila University in Szeged, reunified in 2000 as the University of Szeged), Slovakia (Comenius University of Bratislava, University of Kosice, and the Slovak Academy of Sciences), Germany (University of Potsdam), Turkey (Kocaeli University), Poland (Medical University of Lublin and University of Gdansk), and Estonia (University of Tartu).

Professor Pihlaja also has strong and enduring ties with Finnish industry. As the main coordinator of peat research in Finland, he has served as President of the Finnish Peatland Society. The peat industry is one of the most important natural resource-based industries in Finland. This is where Professor Pihlaja’s has made additional outstanding contributions to environmental chemistry. Besides his scientific achievements in this field, Kalevi has developed a full teaching and research program in Environmental and Natural Products Chemistry at the University of Turku, and after his retirement, the professorship was filled, and the new chair holder was his best doctoral student within natural products chemistry, Dr. Juha-Pekka Salminen. The environmental chemistry component t was later transferred to a European Union Tempus project via the University of Tartu in neighboring Estonia.

Professor Pihlaja has been a most successful educator and propagator of science. As many as 36 doctoral theses have been defended under his supervision within such topics as structural and conformational analysis, mass spectrometry, environmental chemistry, and natural products chemistry, among others. He has also been the main organizer of numerous scientific conferences and meetings in the fields of structural analysis and synthetic and environmental chemistry. He has lectured in more than 20 countries, including Japan and New Zealand. He holds Honorary Doctorates in Pharmacology from Albert Szent-Györgyi Medical University, Hungary (1989) and in Philosophy from University of Åbo Akademi in Turku (2005), Finland, and an Honorary Professorship in Physics from the University of St. Petersburg, Russia (2000). In Finland, Professor Pihlaja has occupied numerous important positions of trust in science and education. He has been a Member of the Finnish Academy of Finland since 1982. In 1995, Kalevi Pihlaja was decorated with the Badge of First Class Knight of the Knights of the White Rose by Finnish President Martti Ahtisaari.

Kalevi is now 80 and still full of life. He has very much left science behind and now focuses on activities for which he earlier did not have enough time. He is, nowadays, even a better cook than earlier, being anointed Chevalier du Bailliage de Finlande (Confrérie de la Chaíne des Rotisseurs) since Oct. 26, 2019. Kalevi has been married to Anne since 1996 (his first and former wife died in 2008, as well as his youngest daughter). Anne’s children have taken to him very well, and he now enjoys being a grandpa for 9 grandchildren. He still enjoys fishing and, nowadays, mainly catches white fish and Baltic herring. Throughout his whole life, Kalevi has been an outstanding community member and he now takes an active part in various voluntary tasks, being now, e.g., a so-called “school grandpa” at Lauste elementary school for the first and second graders.

Prof. Ferenc Fulop
Prof. Dariusz Matosiuk
Guest Editors

Manuscript Submission Information

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Published Papers (5 papers)

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Research

Open AccessArticle
Copper-Catalyzed Trifluoromethylation of Alkoxypyridine Derivatives
Molecules 2020, 25(20), 4766; https://doi.org/10.3390/molecules25204766 - 16 Oct 2020
Abstract
The trifluoromethylation of aromatic and heteroaromatic cores has attracted considerable interest in recent years due to its pharmacological relevance. We studied the extension of a simple copper-catalyzed trifluoromethylation protocol to alkoxy-substituted iodopyridines and their benzologs. The trifluoromethylation proceeded smoothly in all cases, and [...] Read more.
The trifluoromethylation of aromatic and heteroaromatic cores has attracted considerable interest in recent years due to its pharmacological relevance. We studied the extension of a simple copper-catalyzed trifluoromethylation protocol to alkoxy-substituted iodopyridines and their benzologs. The trifluoromethylation proceeded smoothly in all cases, and the desired compounds were isolated and characterized. In the trifluoromethylation of 3-iodo-4-methoxyquinoline, we observed a concomitant O-N methyl migration, resulting in the trifluoromethylated quinolone as a product. Overall, the described procedure should facilitate the broader use of copper-catalyzed trifluoromethylation in medicinal chemistry. Full article
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Open AccessArticle
ESIPT-Related Origin of Dual Fluorescence in the Selected Model 1,3,4-Thiadiazole Derivatives
Molecules 2020, 25(18), 4168; https://doi.org/10.3390/molecules25184168 - 11 Sep 2020
Abstract
In our previous work, we discussed the emergence of the dual fluorescence phenomenon in selected compounds from the group of 1,3,4-thiadiazoles. The results obtained in a number of experimental studies, supported by [TD]DFT calculations, clearly indicated that the phenomenon of dual fluorescence stemmed [...] Read more.
In our previous work, we discussed the emergence of the dual fluorescence phenomenon in selected compounds from the group of 1,3,4-thiadiazoles. The results obtained in a number of experimental studies, supported by [TD]DFT calculations, clearly indicated that the phenomenon of dual fluorescence stemmed from an overlap of several factors, including the correct conformation of the analyzed molecule and, very significantly in this context, aggregation effects. Where those two conditions were met, we could observe the phenomenon of intermolecular charge transfer (CT) and the emergence of electronic states responsible for long wave emissions. However, in light of the new studies presented in this paper, we were able, for the first time, to provide a specific theory for the effect of dual fluorescence observed in the analyzed group of 1,3,4-thiadiazoles. We present the results of spectroscopic measurements conducted for two selected analogues from the 1,3,4-thiadiazole group, both in polar and non-polar solvents, which clearly evidence (as we have already suspected in the past, albeit have not shown in publications to date) the possibility of processes related to emission from the tautomer formed in the process of excited state intramolecular proton transfer, which is responsible for the long-wavelength emissions observed in the selected analogues. The presented results obtained with the use of UV-Vis, fluorescence (stationary and time-resolved), FTIR, and Raman spectroscopy, as well as from calculations of dipole moment changes between the ground and excited state with the use of two derivatives with different structures of the resorcylic system, corroborated our standing hypothesis. At the same time, they excluded the presence of ground state keto forms of the analyzed analogues unless necessitated by the structure of the molecule itself. In this case, aggregation factors enhance the observed effects related to the dual fluorescence of the analyzed compounds (by way of AIE—aggregated induced emissions). Full article
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Open AccessArticle
Synthesis and Anthelmintic Activity of New Thiosemicarbazide Derivatives—A Preliminary Study
Molecules 2020, 25(12), 2770; https://doi.org/10.3390/molecules25122770 - 16 Jun 2020
Cited by 1
Abstract
Parasitic infections caused by different species of intestinal helminths still poses a threat to public health. There is a need to search for new, effective anthelmintic drugs. A series of novel thiosemicarbazides were synthesized and evaluated for their in vitro anthelmintic activity. The [...] Read more.
Parasitic infections caused by different species of intestinal helminths still poses a threat to public health. There is a need to search for new, effective anthelmintic drugs. A series of novel thiosemicarbazides were synthesized and evaluated for their in vitro anthelmintic activity. The preliminary results showed that the most of synthesized compounds were very active. 4-Phenyl-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide and 4-(3-chlorophenyl)-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide showed a 100% mortality of nematodes and a high anthelmintic activity in both tested concentrations. Full article
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Open AccessArticle
An Efficient Greener Approach for N-acylation of Amines in Water Using Benzotriazole Chemistry
Molecules 2020, 25(11), 2501; https://doi.org/10.3390/molecules25112501 - 28 May 2020
Abstract
A straightforward, mild and cost-efficient synthesis of various arylamides in water was accomplished using versatile benzotriazole chemistry. Acylation of various amines was achieved in water at room temperature as well as under microwave irradiation. The developed protocol unfolds the synthesis of amino acid [...] Read more.
A straightforward, mild and cost-efficient synthesis of various arylamides in water was accomplished using versatile benzotriazole chemistry. Acylation of various amines was achieved in water at room temperature as well as under microwave irradiation. The developed protocol unfolds the synthesis of amino acid aryl amides, drug conjugates and benzimidazoles. The environmentally friendly synthesis, short reaction time, simple workup, high yields, mild conditions and free of racemization are the key advantages of this protocol. Full article
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Open AccessArticle
N-Acetylation of Amines in Continuous-Flow with Acetonitrile—No Need for Hazardous and Toxic Carboxylic Acid Derivatives
Molecules 2020, 25(8), 1985; https://doi.org/10.3390/molecules25081985 - 23 Apr 2020
Cited by 2
Abstract
A continuous-flow acetylation reaction was developed, applying cheap and safe reagent, acetonitrile as acetylation agent and alumina as catalyst. The method developed utilizes milder reagent than those used conventionally. The reaction was tested on various aromatic and aliphatic amines with good conversion. The [...] Read more.
A continuous-flow acetylation reaction was developed, applying cheap and safe reagent, acetonitrile as acetylation agent and alumina as catalyst. The method developed utilizes milder reagent than those used conventionally. The reaction was tested on various aromatic and aliphatic amines with good conversion. The catalyst showed excellent reusability and a scale-up was also carried out. Furthermore, a drug substance (paracetamol) was also synthesized with good conversion and yield. Full article
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