How to run a powershell command in c#

So I am attempting to change the creation date of a text file in C#. The user will type in thr creation date of the file, it will then change the text files creation date to what the user inputted. Trouble is it keeps adding a ' for some reason resulting in an error message, it is calling on Powershell to accomplish this:

    public partial class Form6 : Form
    {
        public Form6()
        {
            InitializeComponent();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string dir = textBox1.Text;

            PowerShell ps = PowerShell.Create();



          ps.AddCommand("Get-ChildItem c:\\encryptedmessagehere.txt | % {$_.CreationTime = '"+ dir + "'}");

            ps.Invoke();
        }
    }
}

Trouble is, after the "'}");, it automatically adds another ', incorrecting the powershell command to change the date. Is there a way to stop it from adding the ' at the end?

The returned error is:

System.Management.Automation.CommandNotFoundException HResult=0x80131501 Message=The term 'Get - ChildItem C:\encryptedmessagehere.txt | % {$_.CreationTime = '06/12/12 09:27:03 AM'} ' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

Thank you.

First, you need to use Powersheel.AddScript method instead of Powersheel.AddCommand method.

Second, you can try the following Powershell code to change the creation time of the file.

(Get-ChildItem d:\Test\new.txt).CreationTime =  '2020/09/23'

Finally, you can try the following c# code example to call powershell code in c#.

private void button1_Click(object sender, EventArgs e)
        {
            string datetime= textBox1.Text;
            PowerShell ps = PowerShell.Create();
            string script = string.Format("(Get-ChildItem d:\\New.txt).CreationTime = '{0}'", datetime);
            ps.AddScript(script);
            ps.Invoke();
            MessageBox.Show("Test");
        }