Sed regex printing into a file.txt

I'm connected to a MQTT stream, and I filter out the data by entering :

mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;p}"

into the Ubuntu terminal. This prints the only things that I am interested from the MQTT stream.

Now that I can do this I would like to dump this information into a qwerty.TXT file I've tried mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;w qwerty.txt}" and got the following error sed: -e expression #1, char 0: unmatched '{' I've looked into SED regex, and the examples are that w file.type writes into the file file.type -where type can be .txt for example.

I've also tried mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;p >> qwerty.txt}" , mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;1a qwerty.txt}"

Q: How can I print my filtered MQTT stream into a file named "qwerty.txt"