8 research outputs found
Computational Studies on Selective Adsorption and Molecular Sieving in HKUST-1 Metal – Organic Framework
No full textMetal organic frameworks (MOFs) bring new possibilities by their potential use in catalysis, gas storage/separation and drug delivery.[1-8]
HKUST-1 consists of Cu2+ ions-connectors and four organic ligands. Open metal sites present in the structure have tremendous impact on the selective adsorption. Showing this is the scope of the studies presented in this thesis.
The guest molecules were chosen basing on the possible applications of HKUST-1. It might serve as an air and water purifying agent (from small gases, niacin and urea) or molecular sieve (for separation of small hydrocarbons).
The results of our research suggest that the adsorption of small gases should be performed in a dry environment, otherwise the copper centers will be blocked by water. In case of separation of aromatic hydrocarbons or biologically important molecules, this does not take place.
The defects in the framework have also been taken into account. Thus, the additional calculations with the defective models have been performed. Results show stronger binding of the guests to the defective site, than the non-defective ones.
Investigation of the changes in the IR spectrum after adsorption allowed to confirm and distinguish the binding mechanism.
The research were performed with DFT, using B3-LYP functional [9,10] and the TZVP basis set (Turbomole program), and two for Gaussian: 6-311G(d) for the non-defective structures and mixed[11] (for the defective ones).
1 Lee et al., Chem. Soc. Rev., 2009, 38, 1450
2 Murray et al., Chem. Soc. Rev., 2009, 38, 1294
3 Li et al., Chem. Soc. Rev.,2009, 38, 1477
4 Bonino et al., Chem. Mater., 2008, 20, 4957
5 Britt et al., P. Natl. Acac. Sci. USA, 2008, 105, 11623
6 Dietzel et al., Chem. Commun., 2008, 5125
7 Caskey et al., J. Am. Chem. Soc., 2008, 130, 10870
8 Valenzano et al., J. Phys. Chem. C, 2010, 114, 11185
9 Becke, Phys. Rev. A , 1988, 38, 3098
10 Lee et al., Phys. Rev. B, 1988, 37, 785
11 Roy et al., J. Chem. Theory. Comput., 2008, 4, 102
Interaction of Biologically Important Organic Molecules with the Unsaturated Copper Centers of the HKUST-1 Metal–Organic Framework: an Ab-Initio Study
No full textInteraction of Small Gases with the Unsaturated Metal Centers of the HKUST‑1 Metal Organic Framework
No full textThe
interactions of CO, CO2, OCS, SO2, NO,
NO2, N2O, NH3, PH3, and
other small molecules with the undercoordinated metal centers of the
HKUST-1 metal organic framework are studied by means of density functional
theory. These molecules are potentially harmful for humans and the
environment and are widely studied because of their spectroscopic
properties. In this work, the energetic and vibrational characteristics
of the adsorbed species are calculated. Adsorption energies on the
Cu2+ sites of the paddlewheel have been calculated, and
the order is: NH3 > H2O > PH3 > H2S > SO2 > CO ∼ OCS ∼
CO2 ∼ NyOx > N2 > O2. The results
show that the interactions
can be classified into three categories: (1) weak physisorption, (2)
polarization and electrostatics, and (3) strong acid–base.
Moreover, interesting vibrational properties are calculated especially
for carbonyl sulfide and dinitrogen monoxide, which can be bound via
two different configurations on the metal atoms. The vibrational modes
are shifting in different directions depending on the binding way
of the molecule; e.g., the symmetric stretching of OCS is shifted
by +17 or −16 cm–1 when bound via the oxygen
or the sulfur atom, respectively
Interaction of Biologically Important Organic Molecules with the Unsaturated Copper Centers of the HKUST‑1 Metal–Organic Framework: an Ab-Initio Study
No full textMetal–organic frameworks (MOFs)
provide new possibilities
for their potential use in catalysis, gas storage/separation, and
drug delivery. In this work, a computational study is performed on
the interaction of biologically important organic molecules such as
caffeine, urea, niacin, and glycine with the undercoordinated copper
centers of the HKUST-1 MOF. Density functional theory calculations
are used to identify the adsorption sites of the organic molecules
in HKUST-1 and to calculate their interaction energies. Two types
of interactions are calculated: (i) strong binding via their nitrogen
or oxygen atoms with the copper atoms of the paddlewheel and (ii)
hydrogen bonds with the carboxylate groups of the MOF. Certain molecules
such as caffeine and niacin can interact simultaneously with more
than two paddlewheels, thus making the interactions even stronger.
The interaction energies vary from 75 kJ mol<sup>–1</sup> for
glycine to 200 kJ mol<sup>–1</sup> for caffeine. The confinement
of the guest molecules in the cage windows of the framework can also
create strong interactions. To take into account the effect of coordination
with multiple paddlewheels, a very large model of the HKUST-1 needs
to be used. The numbers of (i) copper sites interacting with the guest
molecule and (ii) hydrogen bonds between the carboxylate groups of
the MOF and the guests have a major impact on binding strength. This
is important information when applying rational design to create new
MOFs that should serve as drug carriers
Interaction of Small Gases with the Unsaturated Metal Centers of the HKUST‑1 Metal Organic Framework
No full textThe
interactions of CO, CO2, OCS, SO2, NO,
NO2, N2O, NH3, PH3, and
other small molecules with the undercoordinated metal centers of the
HKUST-1 metal organic framework are studied by means of density functional
theory. These molecules are potentially harmful for humans and the
environment and are widely studied because of their spectroscopic
properties. In this work, the energetic and vibrational characteristics
of the adsorbed species are calculated. Adsorption energies on the
Cu2+ sites of the paddlewheel have been calculated, and
the order is: NH3 > H2O > PH3 > H2S > SO2 > CO ∼ OCS ∼
CO2 ∼ NyOx > N2 > O2. The results
show that the interactions
can be classified into three categories: (1) weak physisorption, (2)
polarization and electrostatics, and (3) strong acid–base.
Moreover, interesting vibrational properties are calculated especially
for carbonyl sulfide and dinitrogen monoxide, which can be bound via
two different configurations on the metal atoms. The vibrational modes
are shifting in different directions depending on the binding way
of the molecule; e.g., the symmetric stretching of OCS is shifted
by +17 or −16 cm–1 when bound via the oxygen
or the sulfur atom, respectively
Inside Back Cover: TNU-9 Zeolite: Aluminum Distribution and Extra-Framework Sites of Divalent Cations (Chem. Eur. J. 37/2017)
No full textSevere Breakthrough COVID-19 Cases during Six Months of Delta Variant (B.1.617.2) Domination in Poland
No full textThe emergence of a highly transmissible and a more pathogenic B.1.617.2 (delta) variant of SARS-CoV-2 has brought concern over COVID-19 vaccine efficacy and the increased risk of severe breakthrough infections. The objective of this study was to assess the frequency and the clinical characteristics of severe breakthrough COVID-19 cases recorded in 10 Polish healthcare units between 1 June and 31 December 2021, a period during which a rapid surge in the share of B.1.617.2 infections was seen, while a significant number of populations were already fully vaccinated. Overall, 723 individuals who completed the initial vaccination regime (fully vaccinated group) and an additional 18 who received a booster dose were identified—together, they represented 20.8% of all the COVID-19 patients hospitalized during the same period in the same healthcare institutions (0.5% in the case of a group that received a booster dose). Although laboratory and clinical parameters did not differ between both groups, patients who received a booster tended to have lower CRP, IL-6, PCT, and d-dimer levels and they required oxygen therapy less frequently. The most common early COVID-19 symptoms in the studied group were fatigue, cough, fever (>38 °C), and dyspnea. Individuals with no detectable anti-spike IgG antibodies constituted 13%; the odds of being a humoral non-responder to the vaccine were increased in patients aged >70 years. Fully vaccinated patients hospitalized after more than 180 days from the last vaccine dose were significantly older and they were predominantly represented by individuals over 70 years and with comorbidities, particularly cardiovascular disease. Contrary to mRNA vaccines, most patients vaccinated with adenoviral vector vaccines were infected within six months. A total of 102 fatal cases (14% of all deaths among vaccinated individuals; 0.7% in the case of a group that received a booster dose) were recorded, representing 17.6% of all the COVID-19 fatalities recorded in June–December 2021 in the considered healthcare units. The odds of death were significantly increased in men, individuals aged >70 years, patients with comorbidities, and those identified as humoral non-responders to vaccination; in fully vaccinated patients the odds were also increased when the second vaccine dose was given >180 days before the first COVID-19 symptoms. The mortality rate in immunocompromised subjects was 19%. The results indicate that compared to vaccinated individuals, severe COVID-19 and deaths in the unvaccinated group were significantly more prevalent during the B.1.617.2-dominated wave in Poland; and, it highlight the protective role of a booster dose, particularly for more vulnerable individuals
