DFT with B3LYP/6-311++G(d,p) level were used
for all calculations in this work. In biological system, 5-FU-
3H2O has the highest stabilization energy compared to 5-FU-
3NH3, 5-FU dimer, and 5-FU monomer. The chemical interactions
of 2′-deoxyribose radical with uracil and 5-FU radicals
to form 2′-deoxyuridine and 2′-deoxy-5-fluorouridine show
that the difference in stabilization energies, ΔE, for their formation
are quite low which facilitates the exchange reactions
in DNA structure. Size, shape density distributions, and chemical
reactivity sites of 5-FU were obtained by mapping electron
density isosurface with electronic surface. Additionally,
the intermolecular hydrogen bonding in 5-FU (sugarphosphate)
backbone system was simulated by NBO analysis
to describe the role of intermolecular hydrogen bonding on the
structure and chemical reactivity of 5-FU in biological systems.
Molecular docking study of the interaction between 5-
FU and human serum albumin (HSA) indicated that 5-FU
binds to HSAwith low affinity and low specificity compared
to other anticancer drugs.

DFT with B3LYP/6-311++G(d,p) level were used
for all calculations in this work. In biological system, 5-FU-
3H2O has the highest stabilization energy compared to 5-FU-
3NH3, 5-FU dimer, and 5-FU monomer. The chemical interactions
of 2′-deoxyribose radical with uracil and 5-FU radicals
to form 2′-deoxyuridine and 2′-deoxy-5-fluorouridine show
that the difference in stabilization energies, ΔE, for their formation
are quite low which facilitates the exchange reactions
in DNA structure. Size, shape density distributions, and chemical
reactivity sites of 5-FU were obtained by mapping electron
density isosurface with electronic surface. Additionally,
the intermolecular hydrogen bonding in 5-FU (sugarphosphate)
backbone system was simulated by NBO analysis
to describe the role of intermolecular hydrogen bonding on the
structure and chemical reactivity of 5-FU in biological systems.
Molecular docking study of the interaction between 5-
FU and human serum albumin (HSA) indicated that 5-FU
binds to HSAwith low affinity and low specificity compared
to other anticancer drugs.

DFT with B3LYP/6-311++G(d,p) level were used
for all calculations in this work. In biological system, 5-FU-
3H2O has the highest stabilization energy compared to 5-FU-
3NH3, 5-FU dimer, and 5-FU monomer. The chemical interactions
of 2′-deoxyribose radical with uracil and 5-FU radicals
to form 2′-deoxyuridine and 2′-deoxy-5-fluorouridine show
that the difference in stabilization energies, ΔE, for their formation
are quite low which facilitates the exchange reactions
in DNA structure. Size, shape density distributions, and chemical
reactivity sites of 5-FU were obtained by mapping electron
density isosurface with electronic surface. Additionally,
the intermolecular hydrogen bonding in 5-FU (sugarphosphate)
backbone system was simulated by NBO analysis
to describe the role of intermolecular hydrogen bonding on the
structure and chemical reactivity of 5-FU in biological systems.
Molecular docking study of the interaction between 5-
FU and human serum albumin (HSA) indicated that 5-FU
binds to HSAwith low affinity and low specificity compared
to other anticancer drugs.

DFT with B3LYP/6-311++G(d,p) level were used
for all calculations in this work. In biological system, 5-FU-
3H2O has the highest stabilization energy compared to 5-FU-
3NH3, 5-FU dimer, and 5-FU monomer. The chemical interactions
of 2′-deoxyribose radical with uracil and 5-FU radicals
to form 2′-deoxyuridine and 2′-deoxy-5-fluorouridine show
that the difference in stabilization energies, ΔE, for their formation
are quite low which facilitates the exchange reactions
in DNA structure. Size, shape density distributions, and chemical
reactivity sites of 5-FU were obtained by mapping electron
density isosurface with electronic surface. Additionally,
the intermolecular hydrogen bonding in 5-FU (sugarphosphate)
backbone system was simulated by NBO analysis
to describe the role of intermolecular hydrogen bonding on the
structure and chemical reactivity of 5-FU in biological systems.
Molecular docking study of the interaction between 5-
FU and human serum albumin (HSA) indicated that 5-FU
binds to HSAwith low affinity and low specificity compared
to other anticancer drugs.

A new series from thieno[2,3-d] pyrimidine derivatives have been synthesized based on 2-
(ethylmercapto)-4-mercapto-6-phenyl-5-pyrimidine carbonitrile, these compounds used in the synthesis of
many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[40,50:4,5]thieno[2,3-d] pyrimidine
derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C
NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and
anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida
albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella
sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated
for their IC50 values against two cancer cell lines (MCF-7 and HeLa cells) in the presence of Paclitaxel as
reference material. Compound (5g) showed the highest cytotoxicity against MCF-7 (IC50 values about
18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound
(5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared
with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

A new series from thieno[2,3-d] pyrimidine derivatives have been synthesized based on 2-
(ethylmercapto)-4-mercapto-6-phenyl-5-pyrimidine carbonitrile, these compounds used in the synthesis of
many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[40,50:4,5]thieno[2,3-d] pyrimidine
derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C
NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and
anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida
albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella
sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated
for their IC50 values against two cancer cell lines (MCF-7 and HeLa cells) in the presence of Paclitaxel as
reference material. Compound (5g) showed the highest cytotoxicity against MCF-7 (IC50 values about
18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound
(5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared
with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

A new series from thieno[2,3-d] pyrimidine derivatives have been synthesized based on 2-
(ethylmercapto)-4-mercapto-6-phenyl-5-pyrimidine carbonitrile, these compounds used in the synthesis of
many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[40,50:4,5]thieno[2,3-d] pyrimidine
derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C
NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and
anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida
albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella
sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated
for their IC50 values against two cancer cell lines (MCF-7 and HeLa cells) in the presence of Paclitaxel as
reference material. Compound (5g) showed the highest cytotoxicity against MCF-7 (IC50 values about
18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound
(5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared
with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

A new series from thieno[2,3-d] pyrimidine derivatives have been synthesized based on 2-
(ethylmercapto)-4-mercapto-6-phenyl-5-pyrimidine carbonitrile, these compounds used in the synthesis of
many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[40,50:4,5]thieno[2,3-d] pyrimidine
derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C
NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and
anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida
albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella
sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated
for their IC50 values against two cancer cell lines (MCF-7 and HeLa cells) in the presence of Paclitaxel as
reference material. Compound (5g) showed the highest cytotoxicity against MCF-7 (IC50 values about
18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound
(5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared
with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

A new series from thieno[2,3-d] pyrimidine derivatives have been synthesized based on 2-
(ethylmercapto)-4-mercapto-6-phenyl-5-pyrimidine carbonitrile, these compounds used in the synthesis of
many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[40,50:4,5]thieno[2,3-d] pyrimidine
derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C
NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and
anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida
albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella
sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated
for their IC50 values against two cancer cell lines (MCF-7 and HeLa cells) in the presence of Paclitaxel as
reference material. Compound (5g) showed the highest cytotoxicity against MCF-7 (IC50 values about
18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound
(5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared
with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

This paper describes a new method to prepare organic-soluble silver nanoclusters (AgNCs) protected by thiophenol (TP) (1), 4-fluorothiophenol (4-FTP) (2) and 4-methylthiophenol (4-MeTP) (3) ligands. Those ligands was chosen to investigate the effect of the substituting group attached to the thiophenol moiety from the point of withdrawing group (fluorine atom) and donating group (methyl group) and their effect in the stability of silver clusters. The optical properties of the as synthesized silver nanoclusters exhibited a broad surface plasmon resonance (SPR) peaks at 464 nm, 474 nm and 475 nm for Ag@SPhX (X= H, F, and Me), respectively. All the three types of silver nanoclusters (1-3) are highly stable even when being exposed to air as indicated by their absorption spectra. There is almost no change in the intensity of their UV-vis absorption peaks even after 24 hours of air exposure. Therefore, we succeeded in the separation of highly stable silver nanoclusters versus the ambient oxidative condition. The morphology and particles size of the as synthesized nanoclusters were estimated by using transmission electron microscopy (TEM). It was found that, all the three types of silver clusters have a homogenous particle size distribution, with an average particle size of about 2 nm. The average chemical formula and the silver to ligand (Ag/L) ratio were calculated by thermogravimetric analysis (TGA) of the synthesized silver nanoclusters.